Secondary battery, battery pack, electric vehicle, electric power storage system, electric power tool, and electronic apparatus

ABSTRACT

A secondary battery includes: a cathode; an anode; and an electrolytic solution. The anode includes a material including Si, Sn, or both as constituent elements. The electrolytic solution includes an unsaturated cyclic ester carbonate represented by the following Formula (1), 
     
       
         
         
             
             
         
       
     
     where X is a divalent group in which m-number of &gt;C═CR1-R2 and n-number of &gt;CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogen group, a halogen group, a monovalent hydrocarbon group, a monovalent halogenated hydrocarbon group, a monovalent oxygen-containing hydrocarbon group, and a monovalent halogenated oxygen-containing hydrocarbon group; any two or more of the R1 to the R4 are allowed to be bonded to one another; and m and n satisfy m≧1 and n≧0.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.13/690,916 filed Nov. 30, 2012, the entirety of which is incorporatedherein by reference to the extent permitted by law. The presentapplication claims the benefit of priority of Japanese PatentApplication No. JP 2011-280186 filed on Dec. 21, 2011 in the JapanPatent Office, the entirety of which is incorporated by reference hereinto the extent permitted by law.

BACKGROUND

The present technology relates to a secondary battery using a materialcontaining an element such as Si as a constituent element, to a batterypack, an electric vehicle, an electric power storage system, an electricpower tool, and an electronic apparatus that use the secondary battery.

In recent years, various electronic apparatuses such as a mobile phoneand a personal digital assistant (PDA) have been widely used, and it hasbeen strongly demanded to further reduce the size and the weight of theelectronic apparatuses and to achieve their long life. Accordingly, asan electric power source for the electronic apparatuses, a battery, inparticular, a small and light-weight secondary battery capable ofproviding high energy density has been developed. In these days, it hasbeen considered to apply such a secondary battery to various otherapplications represented by a battery pack attachably and detachablymounted on the electronic apparatuses or the like, an electric vehiclesuch as an electric automobile, an electric power storage system such asa home electric power server, and an electric power tool such as anelectric drill.

As the secondary battery, secondary batteries that obtain a batterycapacity by utilizing various charge and discharge principles have beenproposed. Specially, a secondary battery utilizing insertion andextraction of an electrode reactant is considered promising, since sucha secondary battery provides higher energy density than lead batteries,nickel cadmium batteries, and the like.

The secondary battery includes a cathode, an anode, and an electrolyticsolution. The electrolytic solution contains a solvent and anelectrolyte salt. The electrolytic solution functioning as a medium fora charge and discharge reaction largely affects performance of thesecondary battery. Therefore, various studies have been made on thecomposition of the electrolytic solution. Specifically, to suppressbattery degradation at the time of high-voltage charging, explosionhazard due to pressure increase inside a battery, and/or the like, acyclic ester carbonate having one or more carbon-carbon unsaturatedbonds is used as an additive of an electrolytic solution (for example,see Japanese Unexamined Patent Application Publication Nos. 2006-114388,2001-135351, H11-191319, 2000-058122, and 2008-010414; and JapaneseUnexamined Patent Application Publication (Translation of PCTApplication) No. 2004-523073). This kind of cyclic ester carbonate isused not only for a battery system using an electrolytic solution(liquid state battery), but also for a battery system not using anelectrolytic solution (solid state battery) (for example, see JapaneseUnexamined Patent Application Publication No. 2003-017121).

SUMMARY

In recent years, high performance and multi-functions of the electronicapparatuses and the like to which the secondary battery is applied areincreasingly developed. Therefore, further improvement of the batterycharacteristics has been desired.

It is desirable to provide a secondary battery capable of providingsuperior battery characteristics, a battery pack, an electric vehicle,an electric power storage system, an electric power tool, and anelectronic apparatus.

According to an embodiment of the present technology, there is provideda secondary battery including: a cathode; an anode; and an electrolyticsolution. The anode includes a material including Si, Sn, or both asconstituent elements. The electrolytic solution includes an unsaturatedcyclic ester carbonate represented by the following Formula (1),

where X is a divalent group in which m-number of >C═CR1-R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.

According to an embodiment of the present technology, there is provideda battery pack including: a secondary battery; a control sectioncontrolling a used state of the secondary battery; and a switch sectionswitching the used state of the secondary battery according to aninstruction of the control section. The secondary battery includes acathode, an anode, and an electrolytic solution. The anode includes amaterial including Si, Sn, or both as constituent elements. Theelectrolytic solution includes an unsaturated cyclic ester carbonaterepresented by the following Formula (1),

where X is a divalent group in which m-number of >C═CR1-R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.

According to an embodiment of the present technology, there is providedan electric vehicle including: a secondary battery; a conversion sectionconverting electric power supplied from the secondary battery into drivepower; a drive section operating according to the drive power; and acontrol section controlling a used state of the secondary battery. Thesecondary battery includes a cathode, an anode, and an electrolyticsolution. The anode includes a material including Si, Sn, or both asconstituent elements. The electrolytic solution includes an unsaturatedcyclic ester carbonate represented by the following Formula (1),

where X is a divalent group in which m-number of >C═CR1-R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.

According to an embodiment of the present technology, there is providedan electric power storage system including: a secondary battery; one ormore electric devices supplied with electric power from the secondarybattery; and a control section controlling the supplying of the electricpower from the secondary battery to the one or more electric devices.The secondary battery includes a cathode, an anode, and an electrolyticsolution. The anode includes a material including Si, Sn, or both asconstituent elements. The electrolytic solution includes an unsaturatedcyclic ester carbonate represented by the following Formula (1),

where X is a divalent group in which m-number of >C═CR1-R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.

According to an embodiment of the present technology, there is providedan electric power tool including: a secondary battery; and a movablesection being supplied with electric power from the secondary battery.The secondary battery includes a cathode, an anode, and an electrolyticsolution. The anode includes a material including Si, Sn, or both asconstituent elements. The electrolytic solution includes an unsaturatedcyclic ester carbonate represented by the following Formula (1),

where X is a divalent group in which m-number of >C═CR1-R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.

According to an embodiment of the present technology, there is providedan electronic apparatus including a secondary battery as an electricpower supply source. The secondary battery includes a cathode, an anode,and an electrolytic solution, the anode includes a material includingSi, Sn, or both as constituent elements. The electrolytic solutionincludes an unsaturated cyclic ester carbonate represented by thefollowing Formula (1),

where X is a divalent group in which m-number of >C═CR1-R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.

According to the secondary battery according to the embodiment of thepresent technology, since the anode includes a material including Si,Sn, or both as constituent elements, and the electrolytic solutionincludes an unsaturated cyclic ester carbonate, superior batterycharacteristics are obtainable. Further, according to the battery pack,the electric vehicle, the electric power storage system, the electricpower tool, and the electronic apparatus according to the embodiments ofthe present technology, similar effects are obtainable.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, and are intended toprovide further explanation of the technology as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate embodiments and,together with the specification, serve to explain the principles of thetechnology.

FIG. 1 is a cross-sectional view illustrating a configuration of asecondary battery (cylindrical type) according to an embodiment of thepresent technology.

FIG. 2 is a cross-sectional view illustrating an enlarged part of aspirally wound electrode body illustrated in FIG. 1.

FIG. 3 is a perspective view illustrating a configuration of anothersecondary battery (laminated film type) according to the embodiment ofthe present technology.

FIG. 4 is a cross-sectional view taken along a line IV-IV of a spirallywound electrode body illustrated in FIG. 3.

FIG. 5 is a block diagram illustrating a configuration of an applicationexample (battery pack) of the secondary battery.

FIG. 6 is a block diagram illustrating a configuration of an applicationexample (electric vehicle) of the secondary battery.

FIG. 7 is a block diagram illustrating a configuration of an applicationexample (electric power storage system) of the secondary battery.

FIG. 8 is a block diagram illustrating a configuration of an applicationexample (electric power tool) of the secondary battery.

FIG. 9 is an analytical result of SnCoC by XPS.

DETAILED DESCRIPTION

An embodiment of the present technology will be hereinafter described indetail with reference to the drawings. The description will be given inthe following order.

1. Secondary Battery

-   -   1-1. Lithium Ion Secondary Battery (Cylindrical Type)    -   1-2. Lithium Ion Secondary Battery (Laminated Film Type)

2. Applications of Secondary Battery

-   -   2-1. Battery Pack    -   2-2. Electric Vehicle    -   2-3. Electric Power Storage System    -   2-4. Electric Power Tool

[1. Secondary Battery]

First, a description will be given of a secondary battery according toan embodiment of the present technology.

[1-1. Lithium Ion Secondary Battery (Cylindrical Type)]

FIG. 1 and FIG. 2 illustrate cross-sectional configurations of asecondary battery. FIG. 2 illustrates enlarged part of a spirally woundelectrode body 20 illustrated in FIG. 1.

[Whole Configuration of Secondary Battery]

The secondary battery herein described is a lithium ion secondarybattery in which the capacity of an anode 22 is obtained by insertionand extraction of Li (lithium ions) as an electrode reactant.

The secondary battery is what we call a cylindrical type secondarybattery. The secondary battery contains the spirally wound electrodebody 20 and a pair of insulating plates 12 and 13 inside a battery can11 in the shape of a substantially hollow cylinder. In the spirallywound electrode body 20, for example, a cathode 21 and the anode 22 arelayered with a separator 23 in between and are spirally wound.

The battery can 11 has a hollow structure in which one end of thebattery can 11 is closed and the other end of the battery can 11 isopened. The battery can 11 may be made of, for example, Fe, Al, an alloythereof, or the like. The surface of the battery can 11 may be platedwith a metal material such as Ni. The pair of insulating plates 12 and13 is arranged to sandwich the spirally wound electrode body 20 inbetween, and to extend perpendicularly to the spirally wound peripherysurface.

At the open end of the battery can 11, a battery cover 14, a safetyvalve mechanism 15, and a positive temperature coefficient device (PTCdevice) 16 are attached by being swaged with a gasket 17. Thereby, thebattery can 11 is hermetically sealed. The battery cover 14 may be madeof, for example, a material similar to that of the battery can 11. Thesafety valve mechanism 15 and the PTC device 16 are provided inside thebattery cover 14. The safety valve mechanism 15 is electricallyconnected to the battery cover 14 through the PTC device 16. In thesafety valve mechanism 15, in the case where the internal pressurebecomes a certain level or more by internal short circuit, externalheating, or the like, a disk plate 15A inverts to cut electricconnection between the battery cover 14 and the spirally wound electrodebody 20. The PTC device 16 prevents abnormal heat generation resultingfrom a large current. In the PTC device 16, as temperature rises,resistance is increased accordingly. The gasket 17 may be made of, forexample, an insulating material. The surface of the gasket 17 may becoated with asphalt.

In the center of the spirally wound electrode body 20, a center pin 24may be inserted. For example, a cathode lead 25 made of a conductivematerial such as Al is connected to the cathode 21. For example, ananode lead 26 made of a conductive material such as Ni is connected tothe anode 22. The cathode lead 25 is attached to the safety valvemechanism 15, and is electrically connected to the battery cover 14. Theanode lead 26 is attached to the battery can 11, and is electricallyconnected to the battery can 11.

[Cathode]

The cathode 21 has, for example, a cathode active material layer 21B ona single surface or both surfaces of a cathode current collector 21A.The cathode current collector 21A may be made of, for example, aconductive material such as Al, Ni, and stainless steel.

The cathode active material layer 21B contains, as cathode activematerials, one or more of cathode materials capable of inserting andextracting lithium ions. The cathode active material layer 21B mayfurther contain other material such as a cathode binder and a cathodeelectric conductor.

The cathode material is preferably a lithium-containing compound, sincethereby high energy density is obtained. Examples of thelithium-containing compound include a lithium-transition metal compositeoxide and a lithium-transition metal-phosphate compound. The lithiumtransition metal composite oxide is an oxide containing Li and one ormore transition metal elements as constituent elements. Thelithium-transition metal phosphate compound is a compound containing Liand one or more transition metal elements as constituent elements.Specially, it is preferable that the transition metal element be one ormore of Co, Ni, Mn, Fe, and the like, since thereby a higher voltage isobtained. The chemical formula thereof is expressed by, for example,Li_(x)M1O₂ or Li_(y)M2PO₄. In the formula, M1 and M2 represent one ormore transition metal elements. Values of x and y vary according to thecharge and discharge state, and are generally in the range of0.05≦x≦1.10 and 0.05≦y≦1.10.

Examples of the lithium-transition metal composite oxide include LiCoO₂,LiNiO₂, and a lithium-nickel-based composite oxide represented by thefollowing Formula (20). Examples of the lithium transition metalphosphate compound include LiFePO₄ and LiFe_(1-u)Mn_(u)PO₄(u<1), sincethereby a high battery capacity is obtained and superior cyclecharacteristics are obtained. However, a lithium-transition metalcomposite oxide and a lithium transition metal phosphate compound otherthan the foregoing compounds may be used.

LiNi_(1-z)M_(z)O₂  (20)

In Formula (20), M is one or more of Co, Mn, Fe, Al, V, Sn, Mg, Ti, Sr,Ca, Zr, Mo, Tc, Ru, Ta, W, Re, Yb, Cu, Zn, Ba, B, Cr, Si, Ga, P, Sb, andNb. z satisfies 0.005<z<0.5.

In addition thereto, the cathode material may be, for example, an oxide,a disulfide, a chalcogenide, a conductive polymer, or the like. Examplesof the oxide include titanium oxide, vanadium oxide, and manganesedioxide. Examples of the disulfide include titanium disulfide andmolybdenum sulfide. Examples of the chalcogenide include niobiumselenide. Examples of the conductive polymer include sulfur,polyaniline, and polythiophene. However, the cathode material may be amaterial other than the foregoing materials as long as the material isallowed to insert and extract lithium ions.

Examples of the cathode binder include one or more of synthetic rubbers,polymer materials, and the like. Examples of the synthetic rubberinclude a styrene-butadiene-based rubber, a fluorine-based rubber, andethylene propylene diene. Examples of the polymer material includepolyvinylidene fluoride and polyimide.

Examples of the cathode electric conductor include one or more of carbonmaterials and the like. Examples of the carbon materials includegraphite, carbon black, acetylene black, and Ketjen black. The cathodeelectric conductor may be a metal material, a conductive polymer, or thelike as long as the material has electric conductivity.

[Anode]

The anode 22 has, for example, an anode active material layer 22B on asingle surface or both surfaces of an anode current collector 22A.

The anode current collector 22A may be made of, for example, aconductive material such as Cu, Ni, and stainless steel. The surface ofthe anode current collector 22A is preferably roughened. Thereby, due towhat we call an anchor effect, adhesion characteristics of the anodeactive material layer 22B with respect to the anode current collector22A are improved. In this case, it is enough that the surface of theanode current collector 22A in the region opposed to the anode activematerial layer 22B is roughened at minimum. Examples of rougheningmethods include a method of forming fine particles by electrolytictreatment. The electrolytic treatment is a method of providing concavityand convexity by forming fine particles on the surface of the anodecurrent collector 22A by an electrolytic method in an electrolytic bath.A copper foil formed by an electrolytic method is generally called“electrolytic copper foil.”

The anode active material layer 22B contains one or more of anodematerials capable of inserting and extracting lithium ions as anodeactive materials, and may also contain other material such as an anodebinder and an anode electric conductor. Details of the anode binder andthe anode electric conductor are, for example, similar to those of thecathode binder and the cathode electric conductor, respectively. Thechargeable capacity of the anode material is preferably larger than thedischarge capacity of the cathode 21 in order to prevent unintentionalprecipitation of lithium metal at the time of charge and discharge.

The anode material may be, for example, a material (metal-basedmaterial) containing one or more of metal elements and metalloidelements capable of forming an alloy with Li as constituent elements.More specifically, the anode material is a material including Si or Snor both as constituent elements. Si and Sn have a high ability ofinserting and extracting lithium ions, and therefore provide high energydensity.

Such a metal-based material may be a simple substance, an alloy, or acompound, may be two or more thereof, or may have one or more phasesthereof in part or all thereof “Alloy” includes a material containingone or more metal elements and one or more metalloid elements, inaddition to a material configured of two or more metal elements.Further, the “alloy” may contain a nonmetallic element as a constituentelement. Examples of the structure thereof include a solid solution, aeutectic crystal (eutectic mixture), an intermetallic compound, and astructure in which two or more thereof coexist. The simple substancemerely refers to a general simple substance (a small amount of impuritymay be therein contained), and does not necessarily refer to a purity100% simple substance.

Examples of the alloys of Si include a material containing one or moreof elements such as Sn, Ni, Cu, Fe, Co, Mn, Zn, In, Ag, Ti, Ge, Bi, Sb,and Cr as constituent elements other than Si. Examples of the compoundsof Si include a material containing one or more of C, O, and the like asconstituent elements other than Si. For example, the compounds of Si maycontain one or more of the elements described for the alloys of Si asconstituent elements other than Si.

Examples of the alloys of Si and the compounds of Si include SiB₄, SiB₆,Mg₂Si, Ni₂Si, TiSi₂, MoSi₂, CoSi₂, NiSi₂, CaSi₂, CrSi₂, Cu₅Si, FeSi₂,MnSi₂, NbSi₂, TaSi₂, VSi₂, WSi₂, ZnSi₂, SiC, Si₃N₄, Si₂N₂O, SiO_(v)(0<v≦2), and LiSiO. v in SiO_(v) may be in the range of 0.2<v<1.4.

Examples of the alloys of Sn include a material containing one or moreof elements such as Si, Ni, Cu, Fe, Co, Mn, Zn, In, Ag, Ti, Ge, Bi, Sb,and Cr as constituent elements other than Sn. Examples of the compoundsof Sn include a material containing one or more of C, O, and the like asconstituent elements. The compounds of Sn may contain, for example, oneor more of the elements described for the alloys of Sn as constituentelements other than Sn. Examples of the alloys of Sn and the compoundsof Sn include SnO_(w) (0<w≦2), SnSiO₃, LiSnO, and Mg₂Sn.

Specially, as a material containing Sn, for example, a materialcontaining a second constituent element and a third constituent elementin addition to Sn as a first constituent element is preferable. Examplesof the second constituent element include one or more of elements suchas Co, Fe, Mg, Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, Zr, Nb, Mo, Ag, In, Ce,Hf, Ta, W, Bi, and Si. Examples of the third constituent element includeone or more of B, C, Al, P, and the like. In the case where the secondconstituent element and the third constituent element are contained, ahigh battery capacity, superior cycle characteristics, and the like areobtained.

Specially, a material containing Sn, Co, and C as constituent elements(SnCoC-containing material) is preferable. The composition of theSnCoC-containing material is, for example, as follows. That is, the Ccontent is from 9.9 mass % to 29.7 mass % both inclusive, and the ratioof Sn and Co contents (Co/(Sn+Co)) is from 20 mass % to 70 mass % bothinclusive, since high energy density is obtained in such a compositionrange.

It is preferable that the SnCoC-containing material have a phasecontaining Sn, Co, and C. Such a phase is preferably low-crystalline oramorphous. The phase is a reaction phase capable of reacting with Li.Due to existence of the reaction phase, superior characteristics areobtained. The half bandwidth of the diffraction peak obtained by X-raydiffraction of the phase is preferably equal to or greater than 1 degbased on diffraction angle of 2θ in the case where CuKα ray is used as aspecific X ray, and the insertion rate is 1 deg/min. Thereby, lithiumions are more smoothly inserted and extracted, and reactivity with theelectrolytic solution is decreased. It is to be noted that, in somecases, the SnCoC-containing material includes a phase containing asimple substance or part of the respective constituent elements inaddition to the low-crystalline phase or the amorphous phase.

Whether or not the diffraction peak obtained by the X-ray diffractioncorresponds to the reaction phase capable of reacting with Li is allowedto be easily determined by comparison between X-ray diffraction chartsbefore and after electrochemical reaction with Li. For example, if theposition of the diffraction peak after electrochemical reaction with Liis changed from the position of the diffraction peak before theelectrochemical reaction with Li, the obtained diffraction peakcorresponds to the reaction phase capable of reacting with Li. In thiscase, for example, the diffraction peak of the low crystalline reactionphase or the amorphous reaction phase is seen in the range of 2θ=from 20deg to 50 deg both inclusive. Such a reaction phase has, for example,the foregoing respective constituent elements, and the low crystallineor amorphous structure thereof possibly results from existence of Cmainly.

In the SnCoC-containing material, part or all of carbon as a constituentelement are preferably bonded to a metal element or a metalloid elementas other constituent element, since thereby cohesion or crystallizationof Sn and/or the like is suppressed. The bonding state of elements isallowed to be checked by, for example, X-ray photoelectron spectroscopy(XPS). In a commercially available device, for example, as a soft X ray,Al-Kα ray, Mg-Kα ray, or the like is used. In the case where part or allof C are bonded to a metal element, a metalloid element, or the like,the peak of a synthetic wave of is orbit of C (Cis) is shown in a regionlower than 284.5 eV. In the device, energy calibration is made so thatthe peak of 4f orbit of Au atom (Au4f) is obtained in 84.0 eV. At thistime, in general, since surface contamination carbon exists on thematerial surface, the peak of C1s of the surface contamination carbon isregarded as 284.8 eV, which is used as the energy standard. In XPSmeasurement, the waveform of the peak of C1s is obtained as a formincluding the peak of the surface contamination carbon and the peak ofcarbon in the SnCoC-containing material. Therefore, for example,analysis is made by using commercially available software to isolateboth peaks from each other. In the waveform analysis, the position ofthe main peak existing on the lowest bound energy side is the energystandard (284.8 eV).

It is to be noted that the SnCoC-containing material is not limited tothe material configured of only Sn, Co, and C (SnCoC) as constituentelements. That is, the SnCoC-containing material may further contain,for example, one or more of Si, Fe, Ni, Cr, In, Nb, Ge, Ti, Mo, Al, P,Ga, Bi, and the like as constituent elements as necessary.

In addition to the SnCoC-containing material, a material containing Sn,Co, Fe, and C as constituent elements (SnCoFeC-containing material) isalso preferable. The composition of the SnCoFeC-containing material maybe arbitrarily set. For example, the composition in which the Fe contentis set small is as follows. That is, the C content is from 9.9 mass % to29.7 mass % both inclusive, the Fe content is from 0.3 mass % to 5.9mass % both inclusive, and the ratio of contents of Sn and Co(Co/(Sn+Co)) is from 30 mass % to 70 mass % both inclusive. Further, forexample, the composition in which the Fe content is set large is asfollows. That is, the C content is from 11.9 mass % to 29.7 mass % bothinclusive, the ratio of contents of Sn, Co, and Fe ((Co+Fe)/(Sn+Co+Fe))is from 26.4 mass % to 48.5 mass % both inclusive, and the ratio ofcontents of Co and Fe (Co/(Co+Fe)) is from 9.9 mass % to 79.5 mass %both inclusive. In such a composition range, high energy density isobtained. The physical properties (half bandwidth and the like) of theSnCoFeC-containing material are similar to those of the foregoingSnCoC-containing material.

It is to be noted that the anode active material layer 22B may furthercontain one or more of other anode materials capable of inserting andextracting lithium ions as long as the anode active material layer 22Bcontains the foregoing anode material (metal-based material) as an anodeactive material.

Examples of other anode material include a carbon material. In thecarbon material, its crystal structure change at the time of insertionand extraction of lithium ions is extremely small. Therefore, the carbonmaterial provides high energy density and superior cyclecharacteristics. Further, the carbon material functions as an anodeelectric conductor as well. Examples of the carbon material includegraphitizable carbon, non-graphitizable carbon in which the spacing of(002) plane is equal to or greater than 0.37 nm, and graphite in whichthe spacing of (002) plane is equal to or smaller than 0.34 nm. Morespecifically, examples of the carbon material include pyrolytic carbons,cokes, glassy carbon fiber, an organic polymer compound fired body,activated carbon, and carbon blacks. Of the foregoing, examples of thecokes include pitch coke, needle coke, and petroleum coke. The organicpolymer compound fired body is obtained by firing (carbonizing) apolymer compound such as a phenol resin and a furan resin at appropriatetemperature. In addition thereto, the carbon material may be lowcrystalline carbon or amorphous carbon heat-treated at temperature ofabout 1000 deg C. or less. It is to be noted that the shape of thecarbon material may be any of a fibrous shape, a spherical shape, agranular shape, and a scale-like shape.

Further, other anode material may be, for example, a metal oxide, apolymer compound, or the like. Examples of the metal oxide include ironoxide, ruthenium oxide, and molybdenum oxide. Examples of the polymercompound include polyacetylene, polyaniline, and polypyrrole. However,other anode material may be a material other than the foregoingmaterials.

The anode active material layer 22B is formed by, for example, a coatingmethod, a vapor-phase deposition method, a liquid-phase depositionmethod, a spraying method, a firing method (sintering method), or acombination of two or more of these methods. The coating method is amethod in which, for example, after a particulate (powder) anode activematerial is mixed with an anode binder and/or the like, the mixture isdispersed in a solvent such as an organic solvent, and the anode currentcollector is coated with the resultant. Examples of the vapor-phasedeposition method include a physical deposition method and a chemicaldeposition method. Specifically, examples thereof include a vacuumevaporation method, a sputtering method, an ion plating method, a laserablation method, a thermal chemical vapor deposition method, a chemicalvapor deposition (CVD) method, and a plasma chemical vapor depositionmethod. Examples of the liquid-phase deposition method include anelectrolytic plating method and an electroless plating method. Thespraying method is a method in which an anode active material in a fusedstate or a semi-fused state is sprayed. The firing method is, forexample, a method in which after the anode current collector is coatedby a coating method, heat treatment is performed at temperature higherthan the melting point of the anode binder and/or the like. Examples ofthe firing method include a publicly-known technique such as anatmosphere firing method, a reactive firing method, and a hot pressfiring method.

In the secondary battery, as described above, in order to preventlithium metal from being unintentionally precipitated on the anode 22 inthe middle of charge, the electrochemical equivalent of the anodematerial capable of inserting and extracting lithium ions is larger thanthe electrochemical equivalent of the cathode. Further, in the casewhere the open circuit voltage (that is, a battery voltage) at the timeof completely-charged state is equal to or greater than 4.25 V, theextraction amount of lithium ions per unit mass is larger than that inthe case where the open circuit voltage is 4.20 V even if the samecathode active material is used. Therefore, amounts of the cathodeactive material and the anode active material are adjusted accordingly.Thereby, high energy density is obtainable.

[Separator]

The separator 23 separates the cathode 21 from the anode 22, and passeslithium ions while preventing current short circuit resulting fromcontact of both electrodes. The separator 23 is, for example, a porousfilm made of a synthetic resin, ceramics, or the like. The separator 23may be a laminated film in which two or more types of porous films arelaminated. Examples of the synthetic resin includepolytetrafluoroethylene, polypropylene, and polyethylene.

In particular, the separator 23 may include, for example, the foregoingporous film (base material layer) and a polymer compound layer providedon one surface or both surfaces of the base material layer. Thereby,adhesion characteristics of the separator 23 with respect to the cathode21 and the anode 22 are improved, and therefore skewness of the spirallywound electrode body 20 as a spirally wound body is suppressed. Thereby,a decomposition reaction of the electrolytic solution is suppressed, andliquid leakage of the electrolytic solution with which the base materiallayer is impregnated is suppressed. Accordingly, even if charge anddischarge are repeated, the resistance of the secondary battery is lesslikely to be increased, and battery swollenness is suppressed.

The polymer compound layer contains, for example, a polymer materialsuch as polyvinylidene fluoride, since such a polymer material has asuperior physical strength and is electrochemically stable. However, thepolymer material may be a material other than polyvinylidene fluoride.The polymer compound layer is formed as follows, for example. That is,after a solution in which the polymer material is dissolved is prepared,the surface of the base material layer is coated with the solution, andthe resultant is subsequently dried. Alternatively, the base materiallayer may be soaked in the solution and may be subsequently dried.

[Electrolytic Solution]

The separator 23 is impregnated with an electrolytic solution as aliquid electrolyte. The electrolytic solution contains one or more ofunsaturated cyclic ester carbonates represented by the following Formula(1). However, the electrolytic solution may contain other material suchas a solvent and an electrolyte salt.

In Formula (1), X is a divalent group in which m-number of >C═CR1-R2 andn-number of >CR3R4 are bonded in any order. Each of R1 to R4 is one of ahydrogen group, a halogen group, a monovalent hydrocarbon group, amonovalent halogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group. Any two or more of R1 to R4 may be bonded to eachother. m and n satisfy m≧1 and n≧0.

The unsaturated cyclic ester carbonate refers to a cyclic estercarbonate having one or more carbon-carbon double bonds (>C═C<). Theelectrolytic solution contains the unsaturated cyclic ester carbonate.One reason for this is that, in this case, even if the anode 22 containsa metal-based material as an anode active material, the chemicalstability of the electrolytic solution is spectacularly improved.Thereby, a decomposition reaction of the electrolytic solution issignificantly suppressed, and therefore battery characteristics such ascycle characteristics and conservation characteristics are improved.

More specifically, in the case where the anode active material is alow-reactive nonmetal-based material (for example, a carbon material), adecomposition reaction of the electrolytic solution resulting fromreactivity of the carbon material less likely matters at the time ofcharge and discharge. Therefore, battery characteristics are less likelyaffected by presence of the unsaturated cyclic ester carbonate in theelectrolytic solution.

Meanwhile, in the case where the anode active material is ahigh-reactive metal-based material, at the time of charge and discharge,a decomposition reaction of the electrolytic solution resulting fromreactivity of the metal-based material is significant, while high energydensity is obtained. Therefore, battery characteristics largely varyaccording to presence of the unsaturated cyclic ester carbonate in theelectrolytic solution. That is, in the case where the metal-basedmaterial is used, if the electrolytic solution does not contain theunsaturated cyclic ester carbonate, a decomposition reaction of theelectrolytic solution resulting from reactivity of the anode activematerial easily proceeds, and accordingly battery characteristics areeasily lowered. Such a tendency is significant particularly under strictconditions such as a high-temperature environment. However, if theelectrolytic solution contains the unsaturated cyclic ester carbonate, arigid film resulting from the unsaturated cyclic ester carbonate isformed on the surface of the anode 22 at the time of charge anddischarge, and therefore the anode 22 is protected from the electrolyticsolution. Thereby, a decomposition reaction of the electrolytic solutionresulting from reactivity of the anode active material is less likely tobe promoted, and battery characteristics are easily retained.

X in Formula (1) is a group obtained by bonding m-number of >C═CR1-R2 ton-number of >CR3R4 so that the valency becomes divalent as a whole (onebonding hand respectively exists on both ends). Adjacent groups (groupsbonded to each other) may be the same type of group such as >C═CR1-R2and >C═CR1-R2, or may be different from each other such as >C═CR1-R2and >CR3R4. That is, the number (m) of >C═CR1-R2 used for forming thedivalent group and the number (n) of >CR3R4 used for forming thedivalent group may be any number, and the bonding order thereof may alsobe any order.

While >C═CR1-R2 is a divalent unsaturated group having the foregoingcarbon-carbon double bond, >CR3R4 is a divalent saturated group nothaving a carbon-carbon double bond. Since n satisfies n≧0, >CR3R4 as asaturated group is not necessarily included in X. Meanwhile, since m≧1,one or more >C═CR1-R2 as an unsaturated group should be included in Xtypically. Therefore, X may be configured of only >C═CR1-R2, or may beconfigured of both >C═CR1-R2 and >CR3R4. One reason for this is that theunsaturated cyclic ester carbonate should have one or more unsaturatedgroups in its chemical structure thereof

Values of m and n are not particularly limited as long as the conditionsof m≧1 and n≧0 are satisfied. Specially, in the case where >C═CR1-R2 is>C═CH₂ and >CR3R4 is >CH₂, (m+n)≦5 is preferably satisfied. One reasonfor this is that, in this case, the carbon number of X is notexcessively large, and therefore the solubility and the compatibility ofthe unsaturated cyclic ester carbonate are secured.

It is to be noted that any two or more of R1 to R4 in >C═CR1-R2and >CR3R4 may be bonded to each other, and the bonded groups may form aring. As an example, R1 may be bonded to R2, R3 may be bonded to R4, andR2 may be bonded to R3 or R4.

Details of R1 to R4 are described below. R1 to R4 may be the same typeof group, or may be groups different from each other. Any two or threeof R1 to R4 may be the same type of group.

Each type of R1 to R4 is not particularly limited as long as each of R1to R4 is one of a hydrogen group, a halogen group, a monovalenthydrocarbon group, a monovalent halogenated hydrocarbon group, amonovalent oxygen-containing hydrocarbon group, and a monovalenthalogenated oxygen-containing hydrocarbon group. One reason for this isthat, since in this case, X has one or more carbon-carbon double bonds(>C═CR1-R2), the foregoing advantage is obtainable without depending onthe types of R1 to R4.

The halogen group is, for example, one or more of a fluorine group (—F),a chlorine group (—Cl), a bromine group (—Br), an iodine group (—I), andthe like. Specially, the fluorine group is preferable, since a filmresulting from the unsaturated cyclic ester carbonate is thereby easilyformed.

“Hydrocarbon group” is a generic term used to refer to groups configuredof C and H, and may have a straight-chain structure or a branchedstructure having one or more side chains. Examples of the monovalenthydrocarbon group include an alkyl group with carbon number from 1 to 12both inclusive, an alkenyl group with carbon number from 2 to 12 bothinclusive, an alkynyl group with carbon number from 2 to 12 bothinclusive, an aryl group with carbon number from 6 to 18 both inclusive,and a cycloalkyl group with carbon number from 3 to 18 both inclusive.One reason for this is that the foregoing advantage is thereby obtainedwhile the solubility, the compatibility, and the like of the unsaturatedcyclic ester carbonate are secured.

More specific examples of the alkyl group include a methyl group (—CH₃),an ethyl group (—C₂H₅), and a propyl group (—C₃H₇). Examples of thealkenyl group include a vinyl group (—CH═CH₂) and an allyl group(—CH₂—CH═CH₂). Examples of the alkynyl group include an ethynyl group(—C≡CH). Examples of the aryl group include a phenyl group and a naphtylgroup. Examples of the cycloalkyl group include a cyclopropyl group, acyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptylgroup, and a cyclooctyl group.

“Oxygen-containing hydrocarbon group” is a group configured of Otogether with C and H. Examples of the monovalent oxygen-containinghydrocarbon group include an alkoxy group with carbon number from 1 to12 both inclusive. One reason for this is that the foregoing advantageis thereby obtained while the solubility, the compatibility, and thelike of the unsaturated cyclic ester carbonate are secured. Morespecific examples of the alkoxy group include a methoxy group (—OCH₃)and an ethoxy group (—OC₂H₅).

It is to be noted that a group obtained by bonding two or more of theforegoing alkyl group and the like so that whole valency becomesmonovalent may be used. Examples thereof include a group obtained bybonding an alkyl group to an aryl group and a group obtained by bondingan alkyl group to a cycloalkyl group. More specific examples of thegroup obtained by bonding an alkyl group to an aryl group include abenzil group.

“Halogenated hydrocarbon group” is obtained by substituting(halogenating) each of part or all of hydrogen groups (—H) out of theforegoing hydrocarbon group by a halogen group. Types of the halogengroup thereof are as described above. Similarly, “halogenatedoxygen-containing hydrocarbon group” is obtained by substituting each ofpart or all of hydrogen groups out of the foregoing oxygen-containinghydrocarbon group by a halogen group. Types of the halogen group thereofare as described above.

Examples of the monovalent halogenated hydrocarbon group include a groupobtained by halogenating the foregoing alkyl group or the like, forexample. That is, the monovalent halogenated hydrocarbon group is agroup obtained by substituting each of part or all of hydrogen groups ofthe foregoing alkyl group or the like by a halogen group. More specificexamples of the group obtained by halogenating an alkyl group or thelike include a trifluoromethyl group (—CF₃) and a pentafluoroethyl group(—C₂F₅). Further, examples of the monovalent halogenatedoxygen-containing hydrocarbon group include a group obtained bysubstituting each of part or all of hydrogen groups of the foregoingalkoxy group or the like by a halogen group. More specific examples ofthe group obtained by halogenating an alkoxy group or the like include atrifluoromethoxy group (—OCF₃) and a pentafluoroethoxy group (—OC₂F₅).

It is to be noted that each of R1 to R4 may be a group other than theforegoing groups. Specifically, each of R1 to R4 may be, for example, aderivative of each of the foregoing groups. The derivative is obtainedby introducing one or more substituent groups to each of the foregoinggroups. Substituent group types may be arbitrary.

Specially, the unsaturated cyclic ester carbonate is preferablyrepresented by the following Formula (2) or Formula (3). One reason forthis is that, in this case, the foregoing advantage is obtained, andsuch compounds are easily synthesized.

In Formulas (2) and (3), each of R5 to R10 is one of a hydrogen group, ahalogen group, a monovalent hydrocarbon group, a monovalent halogenatedhydrocarbon group, a monovalent oxygen-containing hydrocarbon group, anda monovalent halogenated oxygen-containing hydrocarbon group. R5 and R6may be bonded to each other; and any two or more of R7 to R10 may bebonded to one another.

Focusing attention on a relation between Formula (1) and Formula (2),the unsaturated cyclic ester carbonate represented by Formula (2) has,as X in Formula (1), one unsaturated group (>C═CH₂) correspondingto >C═CR1-R2 and one saturated group (>CR5R6) corresponding to >CR3R4.Meanwhile, focusing attention on a relation between Formula (1) andFormula (3), the unsaturated cyclic ester carbonate represented byFormula (3) has, as X, one unsaturated group (>C═CH₂) correspondingto >C═CR1-R2 and two saturated groups (>CR7R8 and >CR9R10) correspondingto >CR3R4. However, the foregoing one unsaturated group and theforegoing two saturated groups are bonded in order of >CR7R8, >CR9R10,and C═CH₂.

Details of R5 and R6 in Formula (2) and R7 to R10 in Formula (3) aresimilar to those of R1 to R4 in Formula (1), and therefore descriptionsthereof will be omitted.

Specific examples of the unsaturated cyclic ester carbonate includecompounds represented by the following Formula (1-1) to Formula (1-56).Such unsaturated cyclic ester carbonates include a geometric isomer.However, specific examples of the unsaturated cyclic ester carbonate arenot limited to the compounds listed in Formula (1-1) to Formula (1-56).

Specially, Formula (1-1) and the like corresponding to Formula (2) orFormula (1-3) and the like corresponding to Formula (3) are preferable,since thereby a higher effect is obtainable.

Although the content of the unsaturated cyclic ester carbonate in theelectrolytic solution is not particularly limited, specially, thecontent thereof is preferably from 0.01 wt % to 10 wt % both inclusive,and more preferably from 0.1 wt % to 5 wt % both inclusive since therebya higher effect is obtainable.

The solvent used for the electrolytic solution contains one or more ofnonaqueous solvents such as an organic solvent (other than the foregoingunsaturated cyclic ester carbonate).

Examples of the nonaqueous solvents include a cyclic ester carbonate, achain ester carbonate, lactone, a chain carboxylic ester, and nitrile,since thereby a superior battery capacity, superior cyclecharacteristics, superior conservation characteristics, and the like areobtained. Examples of the cyclic ester carbonate include ethylenecarbonate, propylene carbonate, and butylene carbonate. Examples of thechain ester carbonate include dimethyl carbonate, diethyl carbonate,ethyl methyl carbonate, and methylpropyl carbonate. Examples of thelactone include γ-butyrolactone and γ-valerolactone. Examples of thecarboxylic ester include methyl acetate, ethyl acetate, methylpropionate, ethyl propionate, methyl butyrate, methyl isobutyrate,methyl trimethylacetate, and ethyl trimethylacetate. Examples of thenitrile include acetonitrile, glutaronitrile, adiponitrile,methoxyacetonitrile, and 3-methoxypropionitrile.

In addition thereto, the nonaqueous solvent may be 1,2-dimethoxyethane,tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran,1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1,4-dioxane,N,N-dimethylformamide, N-methylpyrrolidinone, N-methyloxazolidinone,N,N′-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane,trimethyl phosphate, and dimethyl sulfoxide. Thereby, a superior batterycapacity and the like are similarly obtained.

Specially, one or more of ethylene carbonate, propylene carbonate,dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate arepreferable, since thereby a superior battery capacity, superior cyclecharacteristics, superior conservation characteristics, and the like areobtained. In this case, a combination of a high viscosity (highdielectric constant) solvent (for example, specific dielectric constant∈≧30) such as ethylene carbonate and propylene carbonate and a lowviscosity solvent (for example, viscosity≦1 mPa·s) such as dimethylcarbonate, ethylmethyl carbonate, and diethyl carbonate is morepreferable. One reason for this is that the dissociation property of theelectrolyte salt and ion mobility are improved.

In particular, the solvent preferably contains one or more of otherunsaturated cyclic ester carbonates represented by the following Formula(4) and Formula (5). One reason for this is that a stable protectivefilm is formed mainly on the surface of the anode 22 at the time ofcharge and discharge, and therefore a decomposition reaction of theelectrolytic solution is suppressed. R11 and R12 may be the same type ofgroup, or may be groups different from each other. Further, R13 to R16may be the same type of group, or may be groups different from eachother. Alternatively, part of R13 to R16 may be the same type of group.The content of other unsaturated cyclic ester carbonate in the solventis not particularly limited, and is, for example, from 0.01 wt % to 10wt % both inclusive. However, specific examples of other unsaturatedcyclic ester carbonate are not limited to the after-mentioned compounds,and other compounds corresponding to Formula (4) and Formula (5) may beused.

In Formula (4), each of R11 and R12 is one of a hydrogen group and analkyl group.

In Formula (5), each of R13 to R16 is one of a hydrogen group, an alkylgroup, a vinyl group, and an allyl group. One or more of R13 to R16 eachare a vinyl group or an allyl group.

Other unsaturated cyclic ester carbonate represented by Formula (4) is avinylene-carbonate-based compound. Each type of R11 and R12 is notparticularly limited as long as each of R11 and R12 is one of a hydrogengroup and an alkyl group. Examples of the alkyl group include a methylgroup and an ethyl group, and the carbon number of the alkyl group ispreferably from 1 to 12 both inclusive, since superior solubility andsuperior compatibility are thereby obtained. Specific examples of thevinylene-carbonate-based compounds include vinylene carbonate(1,3-dioxole-2-one), methylvinylene carbonate(4-methyl-1,3-dioxole-2-one), ethylvinylene carbonate(4-ethyl-1,3-dioxole-2-one), 4,5-dimethyl-1,3-dioxole-2-one, and4,5-diethyl-1,3-dioxole-2-one. It is to be noted that each of R11 andR12 may be a group obtained by substituting each of part or all ofhydrogen groups of the alkyl group by a halogen group. In this case,specific examples of the vinylene-carbonate-based compounds include4-fluoro-1,3-dioxole-2-one and 4-trifluoromethyl-1,3-dioxole-2-one.Specially, vinylene carbonate is preferable, since vinylene carbonate iseasily available and provides a high effect.

Other unsaturated cyclic ester carbonate represented by Formula (5) is avinylethylene carbonate-based compound. Each type of R13 to R16 is notparticularly limited as long as each of R13 to R16 is one of a hydrogengroup, an alkyl group, a vinyl group, and an allyl group, where one ormore of R13 to R16 each are one of a vinyl group and an allyl group. Thetype and the carbon number of the alkyl group are similar to those ofR11 and R12. Specific examples of the vinylethylene carbonate-basedcompounds include vinylethylene carbonate (4-vinyl-1,3-dioxolane-2-one),4-methyl-4-vinyl-1,3-dioxolane-2-one,4-ethyl-4-vinyl-1,3-dioxolane-2-one,4-n-propyl-4-vinyl-1,3-dioxolane-2-one,5-methyl-4-vinyl-1,3-dioxolane-2-one, 4,4-divinyl-1,3-dioxolane-2-one,and 4,5-divinyl-1,3-dioxolane-2-one. Specially, vinylethylene carbonateis preferable, since vinylethylene carbonate is easily available, andprovides a high effect. It is needless to say that all of R13 to R16 maybe vinyl groups or allyl groups. Alternatively, some of R13 to R16 maybe vinyl groups, and the others thereof may be allyl groups.

It is to be noted that other unsaturated cyclic ester carbonate may bethe compounds represented by Formula (4) and Formula (5), or may becatechol carbonate having a benzene ring.

Further, the solvent preferably contains one or more of halogenatedester carbonates represented by the following Formula (6) and Formula(7). One reason for this is that a stable protective film is formedmainly on the surface of the anode 22 at the time of charge anddischarge, and therefore a decomposition reaction of the electrolyticsolution is suppressed. The halogenated ester carbonate represented byFormula (6) is a cyclic ester carbonate having one or more halogens asconstituent elements (halogenated cyclic ester carbonate). Thehalogenated ester carbonate represented by Formula (7) is a chain estercarbonate having one or more halogens as constituent elements(halogenated chain ester carbonate). R17 to R20 may be the same type ofgroup, or may be groups different from each other. Alternatively, partof R17 to R20 may be the same type of group. The same is applied to R21to R26. Although the content of the halogenated ester carbonate in thesolvent is not particularly limited, the content thereof is, forexample, from 0.01 wt % to 50 wt % both inclusive. However, specificexamples of the halogenated ester carbonate are not limited to thecompounds described below, and other compounds corresponding to Formula(6) and Formula (7) may be used.

In Formula (6), each of R17 to R20 is one of a hydrogen group, a halogengroup, an alkyl group, and a halogenated alkyl group. One or more of R17to R20 are each one of a halogen group and a halogenated alkyl group.

In Formula (7), each of R21 to R26 is one of a hydrogen group, a halogengroup, an alkyl group, and a halogenated alkyl group. One or more of R21to R26 are each a halogen group or a halogenated alkyl group.

Although halogen type is not particularly limited, specially, fluorine(F), chlorine (Cl), or bromine (Br) is preferable, and fluorine is morepreferable since thereby a higher effect is obtained compared to otherhalogens. However, the number of halogens is more preferably two thanone, and further may be three or more. One reason for this is that,since thereby an ability of forming a protective film is improved and amore rigid and stable protective film is formed, a decompositionreaction of the electrolytic solution is thereby more suppressed.

Examples of the halogenated cyclic ester carbonate include compoundsrepresented by the following Formula (6-1) to Formula (6-21). Thehalogenated cyclic ester carbonate includes a geometric isomer.Specially, 4-fluoro-1,3-dioxolane-2-one represented by Formula (6-1) or4,5-difluoro-1,3-dioxolane-2-one represented by Formula (6-3) ispreferable, and the latter is more preferable. Further, as4,5-difluoro-1,3-dioxolane-2-one, a trans isomer is more preferable thana cis isomer, since the trans isomer is easily available and provides ahigh effect. Examples of the halogenated chain ester carbonate includefluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, anddifluoromethyl methyl carbonate.

Further, the solvent preferably contains sultone (cyclic sulfonicester), since thereby the chemical stability of the electrolyticsolution is more improved. Examples of sultone include propane sultoneand propene sultone. Although the sultone content in the solvent is notparticularly limited, for example, the sultone content is from 0.5 wt %to 5 wt % both inclusive. Specific examples of sultone are not limitedto the foregoing compounds, and may be other compounds.

Further, the solvent preferably contains an acid anhydride since thechemical stability of the electrolytic solution is thereby furtherimproved. Examples of the acid anhydrides include a carboxylicanhydride, a disulfonic anhydride, and a carboxylic acid sulfonic acidanhydride. Examples of the carboxylic anhydride include a succinicanhydride, a glutaric anhydride, and a maleic anhydride. Examples of thedisulfonic anhydride include an ethane disulfonic anhydride and apropane disulfonic anhydride. Examples of the carboxylic acid sulfonicacid anhydride include a sulfobenzoic anhydride, a sulfopropionicanhydride, and a sulfobutyric anhydride. Although the content of theacid anhydride in the solvent is not particularly limited, for example,the content thereof is from 0.5 wt % to 5 wt % both inclusive. However,specific examples of the acid anhydrides are not limited to theforegoing compounds, and other compound may be used.

The electrolyte salt used for the electrolytic solution may contain, forexample, one or more of salts such as a lithium salt. However, theelectrolyte salt may contain, for example, a salt other than the lithiumsalt (for example, a light metal salt other than the lithium salt).

Examples of the lithium salts include lithium hexafluorophosphate(LiPF₆), lithium tetrafluoroborate (LiBF₄), lithium perchlorate(LiClO₄), lithium hexafluoroarsenate (LiAsF₆), lithium tetraphenylborate(LiB(C₆H₅)₄), lithium methanesulfonate (LiCH₃SO₃), lithiumtrifluoromethane sulfonate (LiCF₃SO₃), lithium tetrachloroaluminate(LiAlCl₄), dilithium hexafluorosilicate (Li₂SiF₆), lithium chloride(LiCl), and lithium bromide (LiBr). Thereby, a superior batterycapacity, superior cycle characteristics, superior conservationcharacteristics, and the like are obtained. However, specific examplesof the lithium salt are not limited to the foregoing compounds, and maybe other compounds.

Specially, one or more of LiPF₆, LiBF₄, LiClO₄, and LiAsF₆ arepreferable, and LiPF₆ is more preferable, since the internal resistanceis thereby lowered, and therefore a higher effect is obtained.

In particular, the electrolyte salt preferably contains one or more ofcompounds represented by the following Formula (8) to Formula (10),since thereby a higher effect is obtained. It is to be noted that R31and R33 may be the same type of group, or may be groups different fromeach other. The same is applied to R41 to R43, R51, and R52. However,specific examples of the compounds represented by Formula (8) to Formula(10) are not limited to the after-mentioned compounds, and othercompounds corresponding to Formula (8) to Formula (10) may be used.

In Formula (8), X31 is one of Group 1 elements, Group 2 elements in thelong-period periodic table, and Al. M31 is one of transition metals,Group 13 elements, Group 14 elements, and Group 15 elements in thelong-period periodic table. R31 is a halogen group. Y31 is one of—C(═O)—R32-C(═O)—, —C(═O)—CR33₂-, and —C(═O)—C(═O)—. R32 is one of analkylene group, a halogenated alkylene group, an arylene group, and ahalogenated arylene group. R33 is one of an alkyl group, a halogenatedalkyl group, an aryl group, and a halogenated aryl group. a3 is one ofinteger numbers 1 to 4 both inclusive. b3 is one of integer numbers 0,2, and 4. Each of c3, d3, m3, and n3 is one of integer numbers 1 to 3both inclusive.

In Formula (9), X41 is one of Group 1 elements and Group 2 elements inthe long-period periodic table. M41 is one of transition metals, Group13 elements, Group 14 elements, and Group 15 elements in the long-periodperiodic table. Y41 is one of —C(═O)—(CR41₂)_(b4)-C(═O)—,—R43₂C—(CR42₂)_(c4)-C(═O)—, —R43₂C—(CR42₂)_(c4)-CR43₂-,—R43₂C—(CR42₂)_(c4)-S(═O)₂—, —S(═O)₂—(CR42₂)_(d4)-S(═O)₂—, and—C(═O)—(CR42₂)_(d4)-S(═O)₂—. Each of R41 and R43 is one of a hydrogengroup, an alkyl group, a halogen group, and a halogenated alkyl group.One or more of R41 and R43 each are the halogen group or the halogenatedalkyl group. R42 is one of a hydrogen group, an alkyl group, a halogengroup, and a halogenated alkyl group. Each of a4, e4, and n4 is one ofinteger numbers 1 and 2. Each of b4 and d4 is one of integer numbers 1to 4 both inclusive. c4 is one of integer numbers 0 to 4 both inclusive.Each of f4 and m4 is one of integer numbers 1 to 3 both inclusive.

In Formula (10), X51 is one of Group 1 elements and Group 2 elements inthe long-period periodic table. M51 is one of transition metals, Group13 elements, Group 14 elements, and Group 15 elements in the long-periodperiodic table. Rf is one of a fluorinated alkyl group with carbonnumber from 1 to 10 both inclusive and a fluorinated aryl group withcarbon number from 1 to 10 both inclusive. Y51 is one of—C(═O)—(CR51₂)_(d5)-C(═O)—, —R52₂C—(CR51₂)_(d5)-C(═O)—,—R52₂C—(CR51₂)_(d5)-CR52₂-, —R52₂C—(CR51₂)_(d5)-S(═O)₂—,—S(═O)₂—(CR51₂)_(e5)-S(—O)₂—, and —C(═O)—(CR⁵¹ ₂)_(e5)-S(—O)₂—. R51 isone of a hydrogen group, an alkyl group, a halogen group, and ahalogenated alkyl group. R52 is one of a hydrogen group, an alkyl group,a halogen group, and a halogenated alkyl group, and one or more thereofeach are a halogen group or a halogenated alkyl group. Each of a5, f5,and n5 is one of integer numbers 1 and 2. Each of b5, c5, and e5 is oneof integer numbers 1 to 4 both inclusive. d5 is one of integer numbers 0to 4 both inclusive. Each of g5 and m5 is one of integer numbers 1 to 3both inclusive.

It is to be noted that Group 1 elements include H, Li, Na, K, Rb, Cs,and Fr. Group 2 elements include Be, Mg, Ca, Sr, Ba, and Ra. Group 13elements include B, Al, Ga, In, and Tl. Group 14 elements include C, Si,Ge, Sn, and Pb. Group 15 elements include N, P, As, Sb, and Bi.

Examples of the compound represented by Formula (8) include compoundsrepresented by Formula (8-1) to Formula (8-6). Examples of the compoundrepresented by Formula (9) include compounds represented by Formula(9-1) to Formula (9-8). Examples of the compound represented by Formula(10) include a compound represented by Formula (10-1).

Further, the electrolyte salt preferably contains one or more ofcompounds represented by the following Formula (11) to Formula (13),since thereby a higher effect is obtained. m and n may be the same valueor values different from each other. The same is applied to p, q, and r.However, specific examples of the compounds represented by Formula (11)to Formula (13) are not limited to compounds described below and othercompounds corresponding to Formula (11) to Formula (13) may be used.

LiN(C_(m)F_(2m+1)SO₂)(C_(n)F_(2n+1)SO₂)  (11)

In Formula (11), each of m and n is an integer number equal to orgreater than 1.

In Formula (12), R61 is a straight-chain or branched perfluoro alkylenegroup with carbon number from 2 to 4 both inclusive.

LiC(C_(p)F_(2p+1)SO₂)(C_(q)F_(2q+1)SO₂)(C_(r)F_(2r+1)SO₂)  (13)

In Formula (13), each of p, q, and r is an integer number equal to orgreater than 1.

The compound represented by Formula (11) is a chain imide compound.Examples thereof include lithium bis(trifluoromethanesulfonyl)imide(LiN(CF₃SO₂)₂), lithium bis (pentafluoroethanesulfonyl)imide(LiN(C₂F₅SO₂)₂), lithium(trifluoromethanesulfonyl)(pentafluoroethanesulfonyl)imide(LiN(CF₃SO₂)(C₂F₅SO₂)),lithium(trifluoromethanesulfonyl)(heptafluoropropanesulfonyl)imide(LiN(CF₃SO₂)(C₃F₇SO₂)), andlithium(trifluoromethanesulfonyl)(nonafluorobutanesulfonyl)imide(LiN(CF₃SO₂)(C₄F₉SO₂)).

The compound represented by Formula (12) is a cyclic imide compound.Examples thereof include compounds represented by Formula (12-1) toFormula (12-4).

The compound represented by Formula (13) is a chain methyde compound.Examples thereof include lithium tris(trifluoromethanesulfonyl)methyde(LiC(CF₃SO₂)₃).

Although the content of the electrolyte salt is not particularlylimited, specially, the content thereof is preferably from 0.3 mol/kg to3.0 mol/kg both inclusive with respect to the nonaqueous solvent, sincethereby high ion conductivity is obtained.

[Operation of Secondary Battery]

In the secondary battery, for example, at the time of charge, lithiumions extracted from the cathode 21 are inserted in the anode 22 throughthe electrolytic solution. Further, at the time of discharge, lithiumions extracted from the anode 22 are inserted in the cathode 21 throughthe electrolyte solution.

[Method of Manufacturing Secondary Battery]

The secondary battery is manufactured, for example, by the followingprocedure.

First, the cathode 21 is formed. A cathode active material is mixed witha cathode binder, a cathode electric conductor, and/or the like toprepare a cathode mixture. Subsequently, the cathode mixture isdispersed in an organic solvent or the like to obtain paste cathodemixture slurry. Subsequently, both surfaces of the cathode currentcollector 21A are coated with the cathode mixture slurry, which is driedto form the cathode active material layer 21B. After that, the cathodeactive material layer 21B is compression-molded by using a roll pressingmachine and/or the like while being heated. In this case,compression-molding may be repeated several times.

Further, the anode 22 is formed by a procedure similar to that of thecathode 21 described above. An anode active material is mixed with ananode binder, an anode electric conductor, and/or the like as necessaryto prepare an anode mixture, which is subsequently dispersed in anorganic solvent or the like to form a paste anode mixture slurry.Subsequently, both surfaces of the anode current collector 22A arecoated with the anode mixture slurry, which is dried to form the anodeactive material layer 22B. After that, the anode active material layer22B is compression-molded as necessary.

Further, after an electrolyte salt is dispersed in a solvent, anunsaturated cyclic ester carbonate is added thereto to prepare anelectrolytic solution.

Finally, the secondary battery is assembled by using the cathode 21 andthe anode 22. First, the cathode lead 25 is attached to the cathodecurrent collector 21A by using a welding method and/or the like, and theanode lead 26 is attached to the anode current collector 22A by using awelding method and/or the like. Subsequently, the cathode 21 and theanode 22 are layered with the separator 23 in between and are spirallywound, and thereby the spirally wound electrode body 20 is formed. Afterthat, the center pin 24 is inserted in the center of the spirally woundelectrode body 20. Subsequently, the spirally wound electrode body 20 issandwiched between the pair of insulating plates 12 and 13, and iscontained in the battery can 11. In this case, the end tip of thecathode lead 25 is attached to the safety valve mechanism 15 by using awelding method and/or the like, and the end tip of the anode lead 26 isattached to the battery can 11 by using a welding method and/or thelike. Subsequently, the electrolytic solution is injected into thebattery can 11, and the separator 23 is impregnated with theelectrolytic solution. Subsequently, at the open end of the battery can11, the battery cover 14, the safety valve mechanism 15, and the PTCdevice 16 are fixed by being swaged with the gasket 17.

[Function and Effect of Secondary Battery]

According to the cylindrical type secondary battery, the anode 22contains the metal-based material and the electrolytic solution containsthe unsaturated cyclic ester carbonate. In this case, as describedabove, the chemical stability of the electrolytic solution isspecifically improved, and therefore a decomposition reaction of theelectrolytic solution is significantly suppressed even if ahigh-reactive metal-based material is used as an anode active material.Therefore, even if the secondary battery is charged and discharged, orstored, the electrolytic solution is less likely to be decomposed, andaccordingly superior battery characteristics are obtainable.

In particular, in the case where the content of the unsaturated cyclicester carbonate in the electrolytic solution is from 0.01 wt % to 10 wt% both inclusive, higher effects are obtainable. Further, in the casewhere the unsaturated cyclic ester carbonate is one of the compoundsrepresented by Formula (1-1) to Formula (1-56), and in particular is thecompound represented by Formula (2) or the compound represented by toFormula (3), higher effects are obtainable.

[1-2. Lithium Ion Secondary Battery (Laminated Film Type)]

FIG. 3 illustrates an exploded perspective configuration of anothersecondary battery. FIG. 4 illustrates an enlarged cross-section takenalong a line IV-IV of a spirally wound electrode body 30 illustrated inFIG. 3. In the following description, the elements of thecylindrical-type secondary battery described above will be used asnecessary.

[Whole Configuration of Secondary Battery]

The secondary battery is what we call a laminated film-type lithium ionsecondary battery. In the secondary battery, the spirally woundelectrode body 30 is contained in a film outer package member 40. In thespirally wound electrode body 30, a cathode 33 and an anode 34 arelayered with a separator 35 and an electrolyte layer 36 in between andare spirally wound. A cathode lead 31 is attached to the cathode 33, andan anode lead 32 is attached to the anode 34. The outermost periphery ofthe spirally wound electrode body 30 is protected by a protective tape37.

The cathode lead 31 and the anode lead 32 are, for example, led out frominside to outside of the outer package member 40 in the same direction.The cathode lead 31 is made of, for example, a conductive material suchas Al, and the anode lead 32 is made of, for example, a conducivematerial such as Cu, Ni, and stainless steel. These conductive materialsare in the shape of, for example, a thin plate or mesh.

The outer package member 40 is a laminated film in which, for example, afusion bonding layer, a metal layer, and a surface protective layer arelaminated in this order. In the laminated film, for example, therespective outer edges of the fusion bonding layers of two films arebonded to each other by fusion bonding, an adhesive, or the like so thatthe fusion bonding layers and the spirally wound electrode body 30 areopposed to each other. Examples of the fusion bonding layer include afilm made of polyethylene, polypropylene, or the like. Examples of themetal layer include an Al foil. Examples of the surface protective layerinclude a film made of nylon, polyethylene terephthalate, or the like.

Specially, as the outer package member 40, an aluminum laminated film inwhich a polyethylene film, an Al foil, and a nylon film are laminated inthis order is preferable. However, the outer package member 40 may bemade of a laminated film having other laminated structure, a polymerfilm such as polypropylene, or a metal film.

An adhesive film 41 to protect from outside air intrusion is insertedbetween the outer package member 40, and the cathode lead 31 and theanode lead 32. The adhesive film 41 is made of a material havingadhesion characteristics with respect to the cathode lead 31 and theanode lead 32. Examples of such an adhesive material include apolyolefin resin such as polyethylene, polypropylene, modifiedpolyethylene, and modified polypropylene.

The cathode 33 has, for example, a cathode active material layer 33B onboth surfaces of a cathode current collector 33A. The anode 34 has, forexample, an anode active material layer 34B on both surfaces of an anodecurrent collector 34A. The configurations of the cathode currentcollector 33A, the cathode active material layer 33B, the anode currentcollector 34A, and the anode active material layer 34B are similar tothe configurations of the cathode current collector 21A, the cathodeactive material layer 21B, the anode current collector 22A, and theanode active material layer 22B, respectively. Therefore, the anodeactive material layer 34B contains a metal-based material as an anodeactive material. Further, the configuration of the separator 35 issimilar to the configuration of the separator 23.

In the electrolyte layer 36, an electrolytic solution is held by apolymer compound. The electrolyte layer 36 is what we call a gelelectrolyte, since thereby high ion conductivity (for example, 1 mS/cmor more at room temperature) is obtained and liquid leakage of theelectrolytic solution is prevented. The electrolyte layer 36 may containother material such as an additive.

Examples of the polymer compound include one or more ofpolyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene,polyhexafluoropropylene, polyethylene oxide, polypropylene oxide,polyphosphazene, polysiloxane, polyvinyl fluoride, polyvinyl acetate,polyvinyl alcohol, polymethacrylic acid methyl, polyacrylic acid,polymethacrylic acid, styrene-butadiene rubber, nitrile-butadienerubber, polystyrene, polycarbonate, and a copolymer of vinylidenefluoride and hexafluoro propylene. Specially, polyvinylidene fluoride orthe copolymer of vinylidene fluoride and hexafluoro propylene ispreferable, and polyvinylidene fluoride is more preferable, since such apolymer compound is electrochemically stable.

The composition of the electrolytic solution is similar to thecomposition of the electrolytic solution of the cylindrical-typesecondary battery. The electrolytic solution contains the unsaturatedcyclic ester carbonate. However, in the electrolyte layer 36 as a gelelectrolyte, the solvent of the electrolytic solution refers to a wideconcept including not only a liquid solvent but also a material havingion conductivity capable of dissociating the electrolyte salt.Therefore, in the case where a polymer compound having ion conductivityis used, the polymer compound is also included in the solvent.

It is to be noted that the electrolytic solution may be used as it is,instead of the gel electrolyte layer 36. In this case, the separator 35is impregnated with the electrolytic solution.

[Operation of Secondary Battery]

In the secondary battery, for example, at the time of charge, lithiumions extracted from the cathode 33 are inserted in the anode 34 throughthe electrolyte layer 36. Meanwhile, at the time of discharge, lithiumions extracted from the anode 34 are inserted in the cathode 33 throughthe electrolyte layer 36.

[Method of Manufacturing Secondary Battery]

The secondary battery including the gel electrolyte layer 36 ismanufactured, for example, by the following three types of procedures.

In the first procedure, the cathode 33 and the anode 34 are formed by aformation procedure similar to that of the cathode 21 and the anode 22.In this case, the cathode 33 is formed by forming the cathode activematerial layer 33B on both surfaces of the cathode current collector33A, and the anode 34 is formed by forming the anode active materiallayer 34B on both surfaces of the anode current collector 34A.Subsequently, a precursor solution containing an electrolytic solution,a polymer compound, and a solvent such as an organic solvent isprepared. After that, the cathode 33 and the anode 34 are coated withthe precursor solution to form the gel electrolyte layer 36.Subsequently, the cathode lead 31 is attached to the cathode currentcollector 33A by using a welding method and/or the like and the anodelead 32 is attached to the anode current collector 34A by using awelding method and/or the like. Subsequently, the cathode 33 and theanode 34 provided with the electrolyte layer 36 are layered with theseparator 35 in between and are spirally wound to form the spirallywound electrode body 30. After that, the protective tape 37 is adheredto the outermost periphery thereof. Subsequently, after the spirallywound electrode body 30 is sandwiched between two pieces of film-likeouter package members 40, the outer edges of the outer package members40 are bonded by a thermal fusion bonding method and/or the like toenclose the spirally wound electrode body 30 into the outer packagemembers 40. In this case, the adhesive films 41 are inserted between thecathode lead 31 and the anode lead 32, and the outer package member 40.

In the second procedure, the cathode lead 31 is attached to the cathode33, and the anode lead 32 is attached to the anode 34. Subsequently, thecathode 33 and the anode 34 are layered with the separator 35 in betweenand are spirally wound to form a spirally wound body as a precursor ofthe spirally wound electrode body 30. After that, the protective tape 37is adhered to the outermost periphery thereof. Subsequently, after thespirally wound body is sandwiched between two pieces of the film-likeouter package members 40, the outermost peripheries except for one sideare bonded by using a thermal fusion bonding method and/or the like toobtain a pouched state, and the spirally wound body is contained in thepouch-like outer package member 40. Subsequently, a composition forelectrolyte containing an electrolytic solution, a monomer as a rawmaterial for the polymer compound, a polymerization initiator, and othermaterials such as a polymerization inhibitor as necessary is prepared,which is injected into the pouch-like outer package member 40. Afterthat, the outer package member 40 is hermetically sealed by using athermal fusion bonding method and/or the like. Subsequently, the monomeris thermally polymerized. Thereby, a polymer compound is formed, andtherefore the gel electrolyte layer 36 is formed.

In the third procedure, the spirally wound body is formed and containedin the pouch-like outer package member 40 in a manner similar to that ofthe foregoing second procedure, except that the separator 35 with bothsurfaces coated with a polymer compound is used. Examples of the polymercompound with which the separator 35 is coated include a polymer (ahomopolymer, a copolymer, or a multicomponent copolymer) containingvinylidene fluoride as a component. Specific examples thereof includepolyvinylidene fluoride, a binary copolymer containing vinylidenefluoride and hexafluoro propylene as components, and a ternary copolymercontaining vinylidene fluoride, hexafluoro propylene, andchlorotrifluoroethylene as components. In addition to the polymercontaining vinylidene fluoride as a component, other one or more polymercompounds may be used. Subsequently, an electrolytic solution isprepared and injected into the outer package member 40. After that, theopening of the outer package member 40 is hermetically sealed by using athermal fusion bonding method and/or the like. Subsequently, theresultant is heated while a weight is applied to the outer packagemember 40, and the separator 35 is adhered to the cathode 33 and theanode 34 with the polymer compound in between. Thereby, the polymercompound is impregnated with the electrolytic solution, and accordinglythe polymer compound is gelated to form the electrolyte layer 36.

In the third procedure, swollenness of the secondary battery issuppressed more than in the first procedure. Further, in the thirdprocedure, the monomer as a raw material of the polymer compound, thesolvent, and the like are less likely to be left in the electrolytelayer 36 compared to in the second procedure. Therefore, the formationstep of the polymer compound is favorably controlled. Therefore,sufficient adhesion characteristics are obtained between the cathode 33,the anode 34, and the separator 35, and the electrolyte layer 36.

[Function and Effect of Secondary Battery]

According to the laminated film-type secondary battery, the anode 34contains the metal-based material, and the electrolytic solution of theelectrolyte layer 36 contains the unsaturated cyclic ester carbonate.Therefore, for a reason similar to that of the cylindrical-typesecondary battery, superior battery characteristics are obtainable.Other functions and other effects are similar to those of thecylindrical-type secondary battery.

[2. Applications of Secondary Battery]

Next, a description will be given of application examples of theforegoing secondary battery.

Applications of the secondary battery are not particularly limited aslong as the secondary battery is used for a machine, a device, aninstrument, an apparatus, a system (collective entity of a plurality ofdevices and the like), or the like that is allowed to use the secondarybattery as a driving electric power source, an electric power storagesource for electric power storage, or the like. In the case where thesecondary battery is used as an electric power source, the secondarybattery may be used as a main electric power source (electric powersource used preferentially), or an auxiliary electric power source(electric power source used instead of a main electric power source orused being switched from the main electric power source). In the lattercase, the main electric power source type is not limited to thesecondary battery.

Examples of applications of the secondary battery include mobileelectronic apparatuss such as a video camcoder, a digital still camera,a mobile phone, a notebook personal computer, a cordless phone, aheadphone stereo, a portable radio, a portable television, and apersonal digital assistant. Further examples thereof include a mobilelifestyle electric appliance such as an electric shaver; a memory devicesuch as a backup electric power source and a memory card; an electricpower tool such as an electric drill and an electric saw; a battery packused as an electric power source of a notebook personal computer or thelike; a medical electronic apparatus such as a pacemaker and a hearingaid; an electric vehicle such as an electric automobile (including ahybrid automobile); and an electric power storage system such as a homebattery system for storing electric power for emergency or the like. Itis needless to say that an application other than the foregoingapplications may be adopted.

Specially, the secondary battery is effectively applicable to thebattery pack, the electric vehicle, the electric power storage system,the electric power tool, the electronic apparatus, or the like. In theseapplications, since superior battery characteristics are demanded, thecharacteristics are allowed to be effectively improved by using thesecondary battery according to the embodiment of the present technology.It is to be noted that the battery pack is an electric power sourceusing a secondary battery, and is what we call an assembled battery orthe like. The electric vehicle is a vehicle that works (runs) by using asecondary battery as a driving electric power source. As describedabove, an automobile including a drive source other than a secondarybattery (such as hybrid automobile) may be included. The electric powerstorage system is a system using a secondary battery as an electricpower storage source. For example, in a home electric power storagesystem, electric power is stored in the secondary battery as an electricpower storage source, and the electric power is consumed. Thereby, homeelectric products and the like become usable. The electric power tool isa tool in which a movable section (such as a drill) is moved by using asecondary battery as a driving electric power source. The electronicapparatus is an apparatus executing various functions by using asecondary battery as a driving electric power source (electric powersupply source).

A description will be specifically given of some application examples ofthe secondary battery. The configurations of the respective applicationexamples explained below are merely examples, and may be changed asappropriate.

[2-1. Battery Pack]

FIG. 5 illustrates a block configuration of a battery pack. For example,as illustrated in FIG. 5, the battery pack includes a control section61, an electric power source 62, a switch section 63, a currentmeasurement section 64, a temperature detection section 65, a voltagedetection section 66, a switch control section 67, a memory 68, atemperature detection device 69, a current detection resistance 70, acathode terminal 71, and an anode terminal 72 in a housing 60 made of aplastic material and/or the like.

The control section 61 controls operations of the whole battery pack(including a used state of the electric power source 62), and includes,for example, a central processing unit (CPU) and/or the like. Theelectric power source 62 includes one or more secondary batteries (notillustrated). The electric power source 62 is, for example, an assembledbattery including two or more secondary batteries. Connection typethereof may be a series-connected type, may be a parallel-connectedtype, or a mixed type thereof. As an example, the electric power source62 includes six secondary batteries connected in a manner ofdual-parallel and three-series.

The switch section 63 switches the used state of the electric powersource 62 (whether or not the electric power source 62 is connectable toan external device) according to an instruction of the control section61. The switch section 63 includes, for example, a charge controlswitch, a discharge control switch, a charging diode, a dischargingdiode, and the like (not illustrated). The charge control switch and thedischarge control switch are, for example, semiconductor switches suchas a field-effect transistor (MOSFET) using metal oxide semiconductor.

The current measurement section 64 measures a current by using thecurrent detection resistance 70, and outputs the measurement result tothe control section 61. The temperature detection section 65 measurestemperature by using the temperature detection device 69, and outputsthe measurement result to the control section 61. The temperaturemeasurement result is used for, for example, a case in which the controlsection 61 controls charge and discharge at the time of abnormal heatgeneration or a case in which the control section 61 performs acorrection processing at the time of calculating a remaining capacity.The voltage detection section 66 measures a voltage of the secondarybattery in the electric power source 62, performs analog-to-digitalconversion (A/D conversion) on the measured voltage, and supplies theresultant to the control section 61.

The switch control section 67 controls operation of the switch section63 according to signals inputted from the current measurement section 64and the voltage measurement section 66.

The switch control section 67 executes control so that a charge currentis prevented from flowing in a current path of the electric power source62 by disconnecting the switch section 63 (charge control switch) in thecase where, for example, a battery voltage reaches an overchargedetection voltage. Thereby, in the electric power source 62, onlydischarge is allowed to be performed through the discharging diode. Itis to be noted that, for example, in the case where a large currentflows at the time of charge, the switch control section 67 blocks thecharge current.

Further, the switch control section 67 executes control so that adischarge current is prevented from flowing in the current path of theelectric power source 62 by disconnecting the switch section 63(discharge control switch) in the case where, for example, a batteryvoltage reaches an overdischarge detection voltage. Thereby, in theelectric power source 62, only charge is allowed to be performed throughthe charging diode. For example, in the case where a large current flowsat the time of discharge, the switch control section 67 blocks thedischarge current.

It is to be noted that, in the secondary battery, for example, theovercharge detection voltage is 4.2 V±0.05 V, and the over-dischargedetection voltage is 2.4 V±0.1 V.

The memory 68 is, for example, an EEPROM as a nonvolatile memory or thelike. The memory 68 stores, for example, numerical values calculated bythe control section 61 and information of the secondary battery measuredin a manufacturing step (such as an internal resistance in the initialstate). It is to be noted that, in the case where the memory 68 stores afull charge capacity of the secondary battery, the control section 61 isallowed to comprehend information such as a remaining capacity.

The temperature detection device 69 measures temperature of the electricpower source 62, and outputs the measurement result to the controlsection 61. The temperature detection device 69 is, for example, athermistor or the like.

The cathode terminal 71 and the anode terminal 72 are terminalsconnected to an external device (such as a notebook personal computer)driven by using the battery pack or an external device (such as abattery charger) used for charging the battery pack.

The electric power source 62 is charged and discharged through thecathode terminal 71 and the anode terminal 72.

[2-2. Electric Vehicle]

FIG. 6 illustrates a block configuration of a hybrid automobile as anexample of electric vehicles. For example, as illustrated in FIG. 6, theelectric vehicle includes a control section 74, an engine 75, anelectric power source 76, a driving motor 77, a differential 78, anelectric generator 79, a transmission 80, a clutch 81, inverters 82 and83, and various sensors 84 in a housing 73 made of a metal. In additionthereto, the electric vehicle includes, for example, a front drive axis85 and a front tire 86 that are connected to the differential 78 and thetransmission 80, a rear drive axis 87, and a rear tire 88.

The electric vehicle is runnable by using one of the engine 75 and themotor 77 as a drive source. The engine 75 is a main power source, andis, for example, a petrol engine. In the case where the engine 75 isused as a power source, drive power (torque) of the engine 75 istransferred to the front tire 86 or the rear tire 88 through thedifferential 78, the transmission 80, and the clutch 81 as drivesections, for example. The torque of the engine 75 is also transferredto the electric generator 79. Due to the torque, the electric generator79 generates alternating-current electric power. The alternating-currentelectric power is converted to direct-current electric power through theinverter 83, and the converted power is stored in the electric powersource 76. On the other hand, in the case where the motor 77 as aconversion section is used as a power source, electric power(direct-current electric power) supplied from the electric power source76 is converted to alternating-current electric power through theinverter 82. The motor 77 is driven by the alternating-current electricpower. Drive power (torque) obtained by converting the electric power bythe motor 77 is transferred to the front tire 86 or the rear tire 88through the differential 78, the transmission 80, and the clutch 81 asthe drive sections, for example.

It is to be noted that, alternatively, the following mechanism may beadopted. In the mechanism, in the case where speed of the electricvehicle is reduced by an unillustrated brake mechanism, the resistanceat the time of speed reduction is transferred to the motor 77 as torque,and the motor 77 generates alternating-current electric power by thetorque. It is preferable that the alternating-current electric power beconverted to direct-current electric power through the inverter 82, andthe direct-current regenerative electric power be stored in the electricpower source 76.

The control section 74 controls operation of the whole electric vehicle,and, for example, includes a CPU and/or the like. The electric powersource 76 includes one or more secondary batteries (not illustrated).Alternatively, the electric power source 76 may be connected to anexternal electric power source, and electric power may be stored byreceiving the electric power from the external electric power source.The various sensors 84 are used, for example, for controlling the numberof revolutions of the engine 75 or for controlling opening level of anunillustrated throttle valve (throttle opening level). The varioussensors 84 include, for example, a speed sensor, an acceleration sensor,an engine frequency sensor, and/or the like.

The description has been hereinbefore given of the hybrid automobile asan electric vehicle. However, examples of the electric vehicles mayinclude a vehicle (electric automobile) working by using only theelectric power source 76 and the motor 77 without using the engine 75.

[2-3. Electric Power Storage System]

FIG. 7 illustrates a block configuration of an electric power storagesystem. For example, as illustrated in FIG. 7, the electric powerstorage system includes a control section 90, an electric power source91, a smart meter 92, and a power hub 93 inside a house 89 such as ageneral residence and a commercial building.

In this case, the electric power source 91 is connected to, for example,an electric device 94 arranged inside the house 89, and is connectableto an electric vehicle 96 parked outside the house 89. Further, forexample, the electric power source 91 is connected to a private powergenerator 95 arranged inside the house 89 through the power hub 93, andis connectable to an external concentrating electric power system 97thorough the smart meter 92 and the power hub 93.

It is to be noted that the electric device 94 includes, for example, oneor more home electric appliances such as a fridge, an air conditioner, atelevision, and a water heater. The private power generator 95 is, forexample, one or more of a solar power generator, a wind-power generator,and the like. The electric vehicle 96 is, for example, one or more of anelectric automobile, an electric motorcycle, a hybrid automobile, andthe like. The concentrating electric power system 97 is, for example,one or more of a thermal power plant, an atomic power plant, a hydraulicpower plant, a wind-power plant, and the like.

The control section 90 controls operation of the whole electric powerstorage system (including a used state of the electric power source 91),and, for example, includes a CPU and/or the like. The electric powersource 91 includes one or more secondary batteries (not illustrated).The smart meter 92 is, for example, an electric power meter compatiblewith a network arranged in the house 89 demanding electric power, and iscommunicable with an electric power supplier. Accordingly, for example,while the smart meter 92 communicates with external as necessary, thesmart meter 92 controls the balance between supply and demand in thehouse 89 and allows effective and stable energy supply.

In the electric power storage system, for example, electric power isstored in the electric power source 91 from the concentrating electricpower system 97 as an external electric power source through the smartmeter 92 and the power hub 93, and electric power is stored in theelectric power source 91 from the private power generator 95 as anindependent electric power source through the power hub 93. Asnecessary, the electric power stored in the electric power source 91 issupplied to the electric device 94 or the electric vehicle 96 accordingto an instruction of the control section 90. Therefore, the electricdevice 94 becomes operable, and the electric vehicle 96 becomeschargeable. That is, the electric power storage system is a systemcapable of storing and supplying electric power in the house 89 by usingthe electric power source 91.

The electric power stored in the electric power source 91 is arbitrarilyusable. Therefore, for example, electric power is allowed to be storedin the electric power source 91 from the concentrating electric powersystem 97 in the middle of the night when an electric rate isinexpensive, and the electric power stored in the electric power source91 is allowed to be used during daytime hours when an electric rate isexpensive.

The foregoing electric power storage system may be arranged for eachhousehold (family unit), or may be arranged for a plurality ofhouseholds (family units).

[2-4. Electric Power Tool]

FIG. 8 illustrates a block configuration of an electric power tool. Forexample, as illustrated in FIG. 8, the electric power tool is anelectric drill, and includes a control section 99 and an electric powersource 100 in a tool body 98 made of a plastic material and/or the like.For example, a drill section 101 as a movable section is attached to thetool body 98 in an operable (rotatable) manner.

The control section 99 controls operation of the whole electric powertool (including a used state of the electric power source 100), andincludes, for example, a CPU and/or the like. The electric power source100 includes one or more secondary batteries (not illustrated). Thecontrol section 99 executes control so that electric power is suppliedfrom the electric power source 100 to the drill section 101 as necessaryaccording to operation of an unillustrated operation switch to operatethe drill section 101.

EXAMPLES

Specific Examples according to the embodiment of the present technologywill be described in detail.

Examples 1-1 to 1-14

The cylindrical-type lithium ion secondary battery illustrated in FIG. 1and FIG. 2 was fabricated by the following procedure.

In forming the cathode 21, first, lithium carbonate (Li₂CO₃) and cobaltcarbonate (CoCO₃) were mixed at a molar ratio of Li₂CO₃:CoCO₃=0.5:1.

Subsequently, the mixture was fired in the air (900 deg C. for 5 hours).Thereby, lithium-cobalt composite oxide (LiCoO₂) was obtained.Subsequently, 91 parts by mass of a cathode active material (LiCoO₂), 3parts by mass of a cathode binder (polyvinylidene fluoride: PVDF), and 6parts by mass of a cathode electric conductor (graphite) were mixed toobtain a cathode mixture. Subsequently, the cathode mixture wasdispersed in an organic solvent (N-methyl-2-pyrrolidone: NMP) to obtaina paste cathode mixture slurry. Subsequently, both surfaces of thecathode current collector 21A in the shape of a strip (Al foil being 20μm thick) were coated with the cathode mixture slurry uniformly by usinga coating device, which was dried to form the cathode active materiallayer 21B. Finally, the cathode active material layer 21B wascompression-molded by using a roll pressing machine.

In forming the anode 22, the anode active material layer 22B was formedby an evaporation method with the use of a metal-based material (Si) asan anode active material. In this case, the anode active material (Si)was deposited on both surfaces of the anode current collector 22A(electrolytic Cu foil being 15 μm thick) by using an electron beamevaporation method. Ten times of deposition steps were repeatedlyperformed so that the thickness of the anode active material layer 22Bon a single surface side of the anode current collector 22A became 6 μm.

For comparison, the anode active material layer 22B was formed by acoating method with the use of a nonmetal-based material (carbonmaterial: C) as an anode active material. In this case, 90 parts by massof an anode active material (artificial graphite) and 10 parts by massof an anode binder (PVDF) were mixed to obtain an anode mixture.Subsequently, the anode mixture was dispersed in an organic solvent(NMP) to obtain a paste anode mixture slurry. Subsequently, bothsurfaces of the anode current collector 22A in the shape of a strip werecoated with the anode mixture slurry uniformly by using a coatingdevice, which was dried to form the anode active material layer 22B.Finally, the anode active material layer 22B was compression-molded byusing a roll pressing machine.

In preparing an electrolytic solution, an electrolyte salt (LiPF₆) wasdissolved in a solvent (ethylene carbonate (EC) and dimethyl carbonate(DMC)). After that, as illustrated in Table 1, an unsaturated cyclicester carbonate was added thereto. In this case, the composition of thesolvent was EC:DMC=50:50 at a weight ratio, and the content of theelectrolyte salt with respect to the solvent was 1 mol/kg.

In assembling the secondary battery, first, the cathode lead 25 made ofAl was welded to the cathode current collector 21A, and the anode lead26 made of Ni was welded to the anode current collector 22A.Subsequently, the cathode 21 and the anode 22 were layered with theseparator 23 (microporous polypropylene film being 25 μm thick) inbetween and were spirally wound. After that, the winding end section wasfixed by using an adhesive tape to form the spirally wound electrodebody 20. Subsequently, the center pin 24 was inserted in the center ofthe spirally wound electrode body 20. Subsequently, while the spirallywound electrode body 20 was sandwiched between the pair of insulatingplates 12 and 13, the spirally wound electrode body 20 was contained inthe battery can 11 made of iron and plated with Ni. In this case, oneend of the cathode lead 25 was welded to the safety valve mechanism 15,and one end of the anode lead 26 was welded to the battery can 11.Subsequently, the electrolytic solution was injected into the batterycan 11 by a depressurization method, and the separator 23 wasimpregnated with the electrolytic solution. Finally, at the open end ofthe battery can 11, the battery cover 14, the safety valve mechanism 15,and the PTC device 16 were fixed by being swaged with the gasket 17. Thecylindrical-type secondary battery was thereby completed. In forming thesecondary battery, lithium metal was prevented from being precipitatedon the anode 22 at the time of full charge by adjusting the thickness ofthe cathode active material layer 21B.

Battery characteristics (cycle characteristics and conservationcharacteristics) of the secondary battery were examined. Resultsillustrated in Table 1 were obtained.

In examining the cycle characteristics, one cycle of charge anddischarge was performed on the secondary battery in the ambienttemperature environment (23 deg C.) to stabilize the battery state.After that, another one cycle of charge and discharge was performed onthe secondary battery in the same environment, and a discharge capacitywas measured. Subsequently, the secondary battery was repeatedly chargedand discharged until the total number of cycles reached 100 in the sameenvironment, and a discharge capacity was measured. From these results,cycle retention ratio (%)=(discharge capacity at the 100thcycle/discharge capacity at the second cycle)×100 was calculated. At thetime of charge, charge was performed at a current of 0.2 C until thevoltage reached the upper limit voltage of 4.2 V, and further charge wasperformed at a constant voltage until the current reached 0.05 C. At thetime of discharge, constant current discharge was performed at a currentof 0.2 C until the voltage reached the final voltage of 2.5 V. “0.2 C”and “0.05 C” are current values at which the battery capacity(theoretical capacity) is fully discharged in 5 hours and 20 hours,respectively.

In examining the conservation characteristics, a secondary battery withits battery state stabilized by a procedure similar to that in the caseof examining the cycle characteristics was used. One cycle of charge anddischarge was performed on the secondary battery in the ambienttemperature environment (23 deg C.), and a discharge capacity wasmeasured. Subsequently, the secondary battery in a state of beingcharged again was stored in a constant temperature bath (80 deg C.) for10 days. After that, the secondary battery was discharged in the ambienttemperature environment (23 deg C.), and a discharge capacity wasmeasured. From these results, conservation retention ratio(%)=(discharge capacity after storage/discharge capacity beforestorage)×100 was calculated. The charge and discharge conditions aresimilar to those in the case of examining the cycle characteristics.

TABLE 1 Unsaturated cyclic Cycle Conservation Anode ester carbonateretention retention active Electrolyte Content ratio ratio Examplematerial salt Solvent Type (wt %) (%) (%) 1-1 Si LiPF₆ EC + DMC Formula0.01 55 78 1-2 (evaporation (1-1) 0.1 58 80 1-3 method) 0.5 60 82 1-4 162 85 1-5 2 64 86 1-6 5 70 86 1-7 10 72 80 1-8 Formula 2 60 84 (1-4) 1-9Formula 2 62 84 (1-16) 1-10 Formula 2 62 82 (1-18) 1-11 Formula 2 62 84(1-32) 1-12 Si LiPF₆ EC + DMC — — 52 74 (evaporation method) 1-13 CLiPF₆ EC + DMC — — 90 92 1-14 (coating Formula 2 90 92 method) (1-1)

In the case where the nonmetal-based material (carbon material) was usedas an anode active material, high cycle retention ratios and highconservation retention ratios were obtained without relation to whetheror not the electrolytic solution contained the unsaturated cyclic estercarbonate. That is, in the case where the carbon material was used, thecycle retention ratios and the conservation retention ratios showed nodifference according to presence of the unsaturated cyclic estercarbonate existed in the electrolytic solution.

Meanwhile, in the case where the metal-based material was used, if theelectrolytic solution contained the unsaturated cyclic ester carbonate,both the cycle retention ratios and the conservation retention ratioswere higher than those in the case where the electrolytic solution didnot contain the unsaturated cyclic ester carbonate.

The result shows the following. That is, in the case where alow-reactive carbon material is used, the carbon material is less likelyto affect the chemical stability (progression of a decompositionreaction) of an electrolytic solution, and therefore a high cycleretention ratio and a high conservation retention ratio are obtainedwithout relation to whether or not an unsaturated cyclic ester carbonateexists. Accordingly, in this case, if the unsaturated cyclic estercarbonate is used, the cycle retention ratio and the conservationretention ratio are not improved. Meanwhile, in the case where ahigh-reactive metal-based material is used, the metal-based materiallargely affects the chemical stability of an electrolytic solution.Therefore, in this case, if the unsaturated cyclic ester carbonate isnot used, only a low cycle retention ratio and only a low conservationretention ratio are obtainable. Meanwhile, in this case, if theunsaturated cyclic ester carbonate is used, the cycle retention ratioand the conservation retention ratio are largely improved.

In particular, in the case where the unsaturated cyclic ester carbonatewas used, if the content thereof was from 0.01 wt % to 10 wt % bothinclusive, more particularly from 0.01 wt % to 5 wt % both inclusive,the cycle retention ratios and the conservation retention ratios werefurther increased.

Examples 2-1 to 2-16

Secondary batteries were fabricated by a procedure similar to that ofExample 1-5, except that the composition of the solvent was changed asillustrated in Table 2, and the respective characteristics wereexamined.

In this case, the following solvents were used in combination with EC.That is, diethyl carbonate (DEC), ethylmethyl carbonate (EMC), andpropyl carbonate (PC) were used. In addition thereto, as otherunsaturated cyclic ester carbonate, vinylene carbonate (VC) was used. Ashalogenated ester carbonates, 4-fluoro-1,3-dioxolane-2-one (FEC),cis-4,5-difluoro-1,3-dioxolane-2-one (c-DFEC),trans-4,5-difluoro-1,3-dioxolane-2-one (t-DFEC), andbis(fluoromethyl)carbonate (DFDMC) were used. As sultone, propenesultone (PRS) was used. As acid anhydrides, succinic anhydride (SCAH)and sulfopropionic anhydride (PSAH) were used.

The composition of the solvent was EC:PC:DMC=10:20:70 at a weight ratio.The content of VC in the solvent was 2 wt %, the content of FEC, c-DFEC,t-DFEC, or DFDMC in the solvent was 5 wt %, and the content of PRS,SCAH, or PSAH in the solvent was 1 wt %.

TABLE 2 Unsaturated cyclic Cycle Conservation Anode ester carbonateretention retention active Electrolyte Content ratio ratio Examplematerial salt Solvent Type (wt %) (%) (%) 2-1 Si LiPF₆ EC + DEC Formula2 64 86 2-2 (evaporation EC + EMC (1-1) 64 87 2-3 method) EC + PC + DMC64 87 2-4 FEC + DMC 82 88 2-5 EC + DMC VC 80 88 2-6 FEC 80 86 2-7 c-DFEC85 86 2-8 t-DFEC 85 86 2-9 DFDMC 78 84 2-10 PRS 64 90 2-11 SCAH 66 902-12 PSAH 68 95 2-13 Si LiPF₆ FEC + DMC — — 80 72 2-14 (evaporation EC +DMC VC 75 76 2-15 method) FEC 75 74 2-16 t-DFEC 82 74

Even if the composition of the solvent was changed, high cycle retentionratios and high conservation retention ratios were obtained. Inparticular, in the case where the electrolytic solution contained otherunsaturated cyclic ester carbonate, the halogenated ester carbonate, thesultone, or the acid anhydride, one or both of the cycle retention ratioand the conservation retention ratio were more increased.

Examples 3-1 to 3-3

Secondary batteries were fabricated by a procedure similar to that ofExample 1-5 except that the composition of the electrolyte salt waschanged as illustrated in Table 3, and the respective characteristicswere examined.

In this case, as an electrolyte salt combined with LiPF₆, lithiumtetrafluoroborate (LiBF₄), bis[oxalato-O,O′] lithium borate (LiBOB)represented by Formula (8-6), or bis(trifluoromethanesulfonyl)imidelithium (LiN(CF₃SO₂)₂: LiTFSI) was used. In this case, the content ofLiPF₆ was 0.9 mol/kg with respect to the solvent, and the content ofLiBF₄ or the like was 0.1 mol/kg with respect to the nonaqueous solvent.

TABLE 3 Unsaturated cyclic Cycle Conservation Anode ester carbonateretention retention active Content ratio ratio Example materialElectrolyte salt Solvent Type (wt %) (%) (%) 3-1 Si LiPF₆ LiBF₄ EC + DMCFormula 2 64 88 3-2 (evaporation LiBOB (1-1) 65 90 3-3 method) LiTFSI 6590

Even if the composition of the electrolyte salt was changed, high cycleretention ratios and high conservation retention ratios were obtained.In particular, in the case where the electrolytic solution containedother electrolyte salt such as LiBF₄, the cycle retention ratio and theconservation retention ratio were more increased.

Examples 4-1 to 4-12, 5-1 to 5-16, and 6-1 to 6-3

Secondary batteries were fabricated by procedures similar to those ofExamples 1-1 to 1-12, 2-1 to 2-16, and 3-1 to 3-3 except the anodeactive material layer 22B was formed by using a sintering method asillustrated in Table 4 to Table 6, and the respective characteristicswere examined.

In forming the anode 22, 90 parts by mass of an anode active material(Si powder) and 10 parts by mass of an anode binder (PVDF) were mixed toobtain an anode mixture. Subsequently, the anode mixture was dispersedin an organic solvent (NMP) to obtain a paste anode mixture slurry.Subsequently, both surfaces of the anode current collector 22A in theshape of a strip were coated with the anode mixture slurry uniformly byusing a coating device. After that, the resultant was fired (350 deg C.for 3 hours).

TABLE 4 Unsaturated cyclic Cycle Conservation Anode ester carbonateretention retention active Electrolyte Content ratio ratio Examplematerial salt Solvent Type (wt %) (%) (%) 4-1 Si LiPF₆ EC + DMC Formula0.01 40 77 4-2 (sintering (1-1) 0.1 45 78 4-3 method) 0.5 48 80 4-4 1 5084 4-5 2 52 86 4-6 5 60 86 4-7 10 62 80 4-8 Formula 2 49 84 (1-4) 4-9Formula 2 50 84 (1-16) 4-10 Formula 2 50 82 (1-18) 4-11 Formula 2 51 84(1-32) 4-12 Si LiPF₆ EC + DMC — — 32 74 (sintering method)

TABLE 5 Unsaturated cyclic Cycle Conservation Anode ester carbonateretention retention active Electrolyte Content ratio ratio Examplematerial salt Solvent Type (wt %) (%) (%) 5-1 Si LiPF₆ EC + DEC Formula2 52 86 5-2 (sintering EC + EMC (1-1) 53 87 5-3 method) EC + PC + DMC 5287 5-4 FEC + DMC 68 88 5-5 EC + DMC VC 65 88 5-6 FEC 66 86 5-7 c-DFEC 7086 5-8 t-DFEC 70 86 5-9 DFDMC 66 84 5-10 PRS 52 90 5-11 SCAH 54 89 5-12PSAH 56 95 5-13 Si LiPF₆ FEC + DEC — — 60 72 5-14 (sintering EC + DMC VC55 76 5-15 method) FEC 55 74 5-16 t-DFEC 62 74

TABLE 6 Unsaturated cyclic Cycle Conservation Anode ester carbonateretention retention active Content ratio ratio Example materialElectrolyte salt Solvent Type (wt %) (%) (%) 6-1 Si LiPF₆ LiBF₄ EC + DMCFormula 2 52 88 6-2 (sintering LiBOB (1-1) 52 90 6-3 method) LiTFSI 5390

Even if the method of forming the anode active material layer 22B waschanged, results similar to those of Table 1 to Table 3 were obtained.That is, in the case where the electrolytic solution contained theunsaturated cyclic ester carbonate, high cycle retention ratios and highconservation retention ratios were obtained. Since other tendencies aresimilar to those described for the results of Table 1 to Table 3,description thereof will be omitted. [Examples 7-1 to 7-4]

Secondary batteries were fabricated by a procedure similar to that ofExamples 1-5, 1-12, 2-6, and 2-15 except that an SnCoC-containingmaterial (SnCoC) was used as a metal-based material, and variouscharacteristics thereof were examined.

In forming the anode 22, Co powder and Sn powder were alloyed to obtainCoSn alloy powder. After that, C powder was added to the resultant andthe resultant was dry-mixed. Subsequently, 10 g of the foregoing mixtureand about 400 g of a corundum being 9 mm in diameter were set in areaction container of a planetary ball mill (available from ItoSeisakusho Co.). Subsequently, inside of the reaction container wassubstituted by Ar atmosphere. After that, 10 minute operation at 250 rpmand 10 minute break were repeated until the total operation time reached20 hours. Subsequently, the reaction container was cooled down to roomtemperature and SnCoC was taken out. After that, the resultant wasscreened through a 280 mesh sieve to remove coarse grain.

The composition of the obtained SnCoC was analyzed. The Sn content was49.5 mass %, the Co content was 29.7 mass %, the C content was 19.8 mass%, and the ratio of Sn and Co (Co/(Sn+Co)) was 37.5 mass %. At thistime, the Sn content and the Co content were measured by inductivelycoupled plasma (ICP) emission analysis, and the C content was measuredby a carbon sulfur analysis device. Further, SnCoC was analyzed by anX-ray diffraction method. A diffraction peak having half bandwidth inthe range of 2θ=20 to 50 deg both inclusive was observed. Further, afterthe SnCoC was analyzed by XPS, as illustrated in FIG. 9, peak P1 wasobtained. After the peak P1 was analyzed, peak P2 of the surfacecontamination carbon and peak P3 of C1s in SnCoC existing on the lowerenergy side (region lower than 284.5 eV) were obtained. From theforegoing results, it was confirmed that C in SnCoC was bonded to otherelement.

After SnCoC was obtained, 80 parts by mass of the anode active material(SnCoC), 8 parts by mass of an anode binder (PVDF), and 12 parts by massof an anode electrical conductor (11 parts by mass of graphite and 1part by mass of acetylene black) were mixed to obtain an anode mixture.Subsequently, the anode mixture was dispersed in an organic solvent(NMP) to obtain a paste anode mixture slurry. Subsequently, bothsurfaces of the anode current collector 22A were uniformly coated withthe anode mixture slurry by a coating device and the resultant was driedto form the anode active material layer 22B. After that, the anodeactive material layer 22B was compression-molded by a rolling pressmachine.

TABLE 7 Unsaturated cyclic Cycle Conservation Anode ester carbonateretention retention active Electrolyte Content ratio ratio Examplematerial salt Solvent Type (wt %) (%) (%) 7-1 SnCoC LiPF₆ EC + DMCFormula 2 80 85 7-2 (coating EC + DMC FEC (1-1) 86 92 method) 7-3 SnCoCLiPF₆ EC + DMC — — 76 70 7-4 (coating EC + DMC FEC 82 80 method)

Even if the metal-based material type was changed, results similar tothose of Table 1 and Table 2 were obtained. That is, in the case wherethe electrolytic solution contained the unsaturated cyclic estercarbonate, high cycle retention ratios and high conservation retentionratios were obtained. Since other tendencies are similar to thosedescribed for the results of Table 1 and Table 2, description thereofwill be omitted.

The present technology has been described with reference to theembodiment and Examples. However, the present technology is not limitedto the examples described in the embodiment and Examples, and variousmodifications may be made. For example, the description has been givenof the lithium ion secondary battery as a secondary battery type.However, applicable secondary battery type is not limited thereto. Thesecondary battery of the present technology is similarly applicable to asecondary battery in which the anode capacity includes a capacity byinserting and extracting lithium ions and a capacity associated withprecipitation and dissolution of lithium metal, and the battery capacityis expressed by the sum of these capacities. In this case, an anodematerial capable of inserting and extracting lithium ions is used as ananode active material, and the chargeable capacity of the anode materialis set to a smaller value than the discharge capacity of the cathode.

Further, the description has been given with the specific examples ofthe case in which the battery structure is the cylindrical type or thelaminated film type, and the battery device has the spirally woundstructure. However, applicable structures are not limited thereto. Thesecondary battery of the present technology is similarly applicable to abattery having other battery structure such as a square-type battery, acoin-type battery, and a button-type battery or a battery in which thebattery device has other structure such as a laminated structure.

Further, the description has been given of the case using Li as anelectrode reactant. However, the electrode reactant is not necessarilylimited thereto. As an electrode reactant, for example, other Group 1elements such as Na and K, a Group 2 element such as Mg and Ca, or otherlight metal such as Al may be used. The effect of the present technologymay be obtained without depending on the electrode reactant type, andtherefore even if the electrode reactant type is changed, a similareffect is obtainable.

Further, with regard to the content of the unsaturated cyclic estercarbonate, the description has been given of the appropriate rangederived from the results of Examples. However, the description does nottotally deny a possibility that the content is out of the foregoingrange. That is, the foregoing appropriate range is the rangeparticularly preferable for obtaining the effects of the presenttechnology. Therefore, as long as the effects of the present technologyare obtained, the content may be out of the foregoing range in somedegrees.

It is possible to achieve at least the following configurations from theabove-described exemplary embodiment and the modifications of thedisclosure.

(1) A secondary battery including:

a cathode;

an anode; and

an electrolytic solution, wherein

the anode includes a material including Si, Sn, or both as constituentelements, and

the electrolytic solution includes an unsaturated cyclic ester carbonaterepresented by the following Formula (1),

where X is a divalent group in which m-number of >C═CR1-R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.(2) The secondary battery according to (1), wherein

the halogen group includes a fluorine group, a chlorine group, a brominegroup, and an iodine group, and

each of the monovalent hydrocarbon group, the monovalent halogenatedhydrocarbon group, the monovalent oxygen-containing hydrocarbon group,and the monovalent halogenated oxygen-containing hydrocarbon groupinclude an alkyl group with carbon number from 1 to 12 both inclusive,an alkenyl group with carbon number from 2 to 12 both inclusive, analkynyl group with carbon number from 2 to 12 both inclusive, an arylgroup with carbon number from 6 to 18 both inclusive, a cycloalkyl groupwith carbon number from 3 to 18 both inclusive, an alkoxy group withcarbon number from 1 to 12 both inclusive, a group obtained by bondingtwo or more thereof, and a group obtained by substituting each of partor all of hydrogen groups thereof by a halogen group.

(3) The secondary battery according to (1) or (2), wherein theunsaturated cyclic ester carbonate is represented by one of thefollowing Formula (2) and Formula (3),

where each of R5 to R10 is one of a hydrogen group, a halogen group, amonovalent hydrocarbon group, a monovalent halogenated hydrocarbongroup, a monovalent oxygen-containing hydrocarbon group, and amonovalent halogenated oxygen-containing hydrocarbon group; the R5 andthe R6 are allowed to be bonded to each other; and any two or more ofthe R7 to the R10 are allowed to be bonded to one another.(4) The secondary battery according to (1) or (2), wherein theunsaturated cyclic ester carbonate is represented by one of thefollowing Formula (1-1) to Formula (1-56),

(5) The secondary battery according to any one of (1) to (4), wherein acontent of the unsaturated cyclic ester carbonate in the electrolyticsolution is from about 0.01 weight percent to about 10 weight percentboth inclusive.(6) The secondary battery according to any one of (1) to (5), whereinthe material including Si, Sn, or both as constituent elements is one ormore of a simple substance, an alloy, and a compound of Si, and a simplesubstance, an alloy, and a compound of Sn.(7) The secondary battery according to any one of (1) to (6), whereinthe secondary battery is a lithium ion secondary battery.(8) A battery pack including:

the secondary battery according to any one of (1) to (7);

a control section controlling a used state of the secondary battery; and

a switch section switching the used state of the secondary batteryaccording to an instruction of the control section.

(9) An electric vehicle including:

the secondary battery according to any one of (1) to (7);

a conversion section converting electric power supplied from thesecondary battery into drive power;

a drive section operating according to the drive power; and

a control section controlling a used state of the secondary battery.

(10) An electric power storage system including:

the secondary battery according to any one of (1) to (7);

one or more electric devices supplied with electric power from thesecondary battery; and

a control section controlling the supplying of the electric power fromthe secondary battery to the one or more electric devices.

(11) An electric power tool including:

the secondary battery according to any one of (1) to (7); and

a movable section being supplied with electric power from the secondarybattery.

(12) An electronic apparatus including the secondary battery accordingto any one of (1) to (7) as an electric power supply source.

The present disclosure contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2011-280186 filed in theJapanese Patent Office on Dec. 21, 2011, the entire contents of which ishereby incorporated by reference.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alternations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof

What is claimed is:
 1. A secondary battery comprising: a cathode; ananode; and an electrolytic solution, wherein, the anode includes amaterial including as constituent elements (a) Si, Sn, or both and (b)C, O, or both, and the electrolytic solution includes an unsaturatedcyclic ester carbonate represented by the following Formula (1):

where X is a divalent group in which m-number of >C═CR1-R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.
 2. The secondarybattery according to claim 1, wherein: the halogen group includes afluorine group, a chlorine group, a bromine group, and an iodine group,and each of the monovalent hydrocarbon group, the monovalent halogenatedhydrocarbon group, the monovalent oxygen-containing hydrocarbon group,and the monovalent halogenated oxygen-containing hydrocarbon groupinclude an alkyl group with carbon number from 1 to 12 both inclusive,an alkenyl group with carbon number from 2 to 12 both inclusive, analkynyl group with carbon number from 2 to 12 both inclusive, an arylgroup with carbon number from 6 to 18 both inclusive, a cycloalkyl groupwith carbon number from 3 to 18 both inclusive, an alkoxy group withcarbon number from 1 to 12 both inclusive, a group obtained by bondingtwo or more thereof, and a group obtained by substituting each of partor all of hydrogen groups thereof by a halogen group.
 3. The secondarybattery according to claim 1, wherein the unsaturated cyclic estercarbonate is represented by one of the following Formula (2) and Formula(3),

where each of R5 to R10 is one of a hydrogen group, a halogen group, amonovalent hydrocarbon group, a monovalent halogenated hydrocarbongroup, a monovalent oxygen-containing hydrocarbon group, and amonovalent halogenated oxygen-containing hydrocarbon group; the R5 andthe R6 are allowed to be bonded to each other; and any two or more ofthe R7 to the R10 are allowed to be bonded to one another.
 4. Thesecondary battery according to claim 1, wherein the unsaturated cyclicester carbonate is represented by one of the following Formula (1-1) toFormula (1-56):


5. The secondary battery according to claim 1, wherein a content of theunsaturated cyclic ester carbonate in the electrolytic solution is fromabout 0.01 weight percent to about 10 weight percent both inclusive. 6.The secondary battery according to claim 1, wherein the materialincluding Si, Sn, or both as constituent elements is one or more of asimple substance, an alloy, and a compound of Si, and a simplesubstance, an alloy, and a compound of Sn.
 7. The secondary batteryaccording to claim 1, wherein the secondary battery is a lithium ionsecondary battery.
 8. A battery pack comprising: a secondary battery; acontrol section controlling a used state of the secondary battery; and aswitch section switching the used state of the secondary batteryaccording to an instruction of the control section, wherein thesecondary battery includes a cathode, an anode including as constituentelements (a) Si, Sn, or both and (b) C, O, or both, and an electrolyticsolution including an unsaturated cyclic ester carbonate represented bythe following Formula (1):

where X is a divalent group in which m-number of >C═CR1-R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.
 9. An electricvehicle comprising: a secondary battery; a conversion section convertingelectric power supplied from the secondary battery into drive power; adrive section operating according to the drive power; and a controlsection controlling a used state of the secondary battery, wherein thesecondary battery includes a cathode, an anode having as constituentelements (a) Si, Sn, or both and (b) C, O, or both, and an electrolyticsolution including an unsaturated cyclic ester carbonate represented bythe following Formula (1):

where X is a divalent group in which m-number of >C═CR1-R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.
 10. An electricpower storage system comprising: a secondary battery; one or moreelectric devices supplied with electric power from the secondarybattery; and a control section controlling the supplying of the electricpower from the secondary battery to the one or more electric devices,wherein the secondary battery includes a cathode, an anode having asconstituent elements (a) Si, Sn, or both and (b) C, O, or both, and anelectrolytic solution including an unsaturated cyclic ester carbonaterepresented by the following Formula (1),

where X is a divalent group in which m-number of >C═CR1-R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.
 11. An electricpower tool comprising: a secondary battery; and a movable section beingsupplied with electric power from the secondary battery, wherein, thesecondary battery includes a cathode, an anode having as constituentelements (a) Si, Sn, or both and (b) C, O, or both, and an electrolyticsolution including an unsaturated cyclic ester carbonate represented bythe following Formula (1),

where X is a divalent group in which m-number of >C═CR1-R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.
 12. Anelectronic apparatus comprising a secondary battery as an electric powersupply source, wherein the secondary battery includes: a cathode, ananode having as constituent elements (a) Si, Sn, or both and (b) C, O,or both, and an electrolytic solution including an unsaturated cyclicester carbonate represented by the following (1),

where X is a divalent group in which m-number of >C═CR1-R2 and n-numberof >CR3R4 are bonded in any order; each of R1 to R4 is one of a hydrogengroup, a halogen group, a monovalent hydrocarbon group, a monovalenthalogenated hydrocarbon group, a monovalent oxygen-containinghydrocarbon group, and a monovalent halogenated oxygen-containinghydrocarbon group; any two or more of the R1 to the R4 are allowed to bebonded to one another; and m and n satisfy m≧1 and n≧0.